12064 research outputs found
Sort by
Chitosan/poly(acrylic acid) polyelectrolyte multilayer: preparation, swelling and self-healing of a nanofilm
No full textUspješno su pripravljeni višeslojevi kitozan/poli(akrilna kiselina) s različitim brojem slojeva na
površini supstrata od silicija. Elipsometrijskim mjerenjima dokazan je eksponencijalni rast
debljine filma s brojem adsorbiranih slojeva i ireverzibilnost procesa bubrenja filma. Ni jedan
od pripravljenih polielektrolitnih višeslojeva nije pokazao značajniju promjenu debljine s
promjenom relativne vlažnosti atmosfere kojoj su bili izloženi. Međutim, pomalo neočekivano
većini uzoraka se smanjila debljina prilikom izlaganja visokoj relativnoj vlažnosti. Kako bi se
detaljnije istražio ovaj efekt, mikroskopom atomskih sila snimljena je površina desetoslojnog
filma prije i nakon izlaganja nanofilma visokoj relativnoj vlažnosti. Na snimkama je uočeno da
se gustoća otoka koje formiraju polielektroliti na površini supstrata smanjila nakon ovakvog
tretmana višesloja što bi moglo biti zbog reorganizacije polielektrolitnih lanaca. Na kraju je
digitalnim optičkim mikroskopom praćeno samozacjeljivanje mehanički oštećenog filma od 60
slojeva. Film je neznatno zacijelio pri visokoj relativnoj vlažnosti, dok je uporabom
deionizirane vode na oštećenju došlo do značajnijeg samozacjeljivanja.Chitosan/poly(acrylic acid) multilayers with different numbers of layers were successfully
prepared on the surface of a silicon substrate. Ellipsometric measurements have shown the
exponential increase in the thickness of the multilayer with the increasing number of layers and
the irreversibility of the swelling process. None of the prepared films showed an increase in
thickness by changing the relative humidity they were exposed to. Unexpectedly, the films have
shown a large decrease in their thickness when they were exposed to high relative humidity. In
order to investigate this phenomenon, a surface of the 10-layered film was imaged by atomic
force microscope before and after exposure of the nanofilm to high relative humidity.
Microscopy scans have shown a decrease in the density of polyelectrolyte islands on a substrate
surface caused by this treatment. The reason for that is probably the reorganization of
polyelectrolyte chains. Self-healing of the mechanically damaged film of 60 layers was
monitored with a digital optical microscope. At high relative humidity, the film heals slightly,
while the use of deionized water on the damaged region caused much more pronounced selfhealing
DNA repair protein expression in testis of mice with a homozygous mutation in the SPRTN gene
No full textSpermatogeneza je složen proces reguliran velikim brojem gena. Identifikacija specifičnih
proteina u tkivu testisa ključna je za razumijevanje pravilnog razvoja zametnih stanica. U ovoj
studiji istražili smo mijenja li se ekspresija proteina koji imaju ulogu u spermatogenezi i popravku
DNA s obzirom na poremećaj funkcije proteina Spartan. Protein Spartan (kodiran SPRTN genom)
uklanja DNA lezije koje mogu zaustaviti replikaciju i dovesti do nastanka dvolančanih lomova i
genomske nestabilnosti. Mutacije u genu SPRTN uzrokuju nastanak hepatocelularnog karcinoma
te sindroma preuranjenog starenja nazvanog Ruijs-Aalfs, poznatog i kao Spartan sindrom. U
ranijim studijama je dokazana veća ekspresija SPRTN gena u testisima u odnosu na ostala tkiva
što ukazuje na njegovu važnu ulogu u tkivu testisa. U našoj studiji testirali smo promjene izražaja
odabranih proteina uključenih u održavanje stabilnosti DNA i replikaciju. Imunohistokemijskom
metodom pokazali smo da postoji promijenjena ekspresija pojedinih proteina u tkivu testisa miševa
s homozigotnom mutacijom u genu SPRTN.Spermatogenesis is a complex process regulated by a large number of genes. Identification
of specific proteins in testicular tissue is important for development of germ cells. In this study,
we investigated whether the expression of proteins that play a role in spermatogenesis and DNA
repair changes with dysfunction of Spartan protein. The Spartan protein (encoded by the SPRTN
gen) removes DNA lesions that can stop replication and lead to double-stranded breaks and
genomic instability. Mutations in the SPRTN gene cause hepatocellular carcinoma and a syndrome
of premature aging called Ruijs-Aalfs, also known as Spartan syndrome. Previous studies have
shown greater expression of the SPRTN gene in the testes compared to other tissues indicating its
important role in testicular tissue. By immunohistochemical method, we showed that there is an
altered expression of certain proteins in testis tissue of mice with a homozygous mutation in the
SPRTN gene
Functional metagenomic analysis of a partial nitritation-anammox bioreactor
No full textOtpadne vode prije ispuštanja u okoliš potrebno je obraditi radi uklanjanja tvari koje bi u
prirodnim vodama izazvale ekološki štetnu eutrofikaciju. Za uklanjanje dušikovih spojeva
uglavnom se koriste bioreaktori različitih tipova. U ovom radu korištene su bioinformatičke
metode za taksonomsku i funkcionalnu analizu metagenoma bioreaktora laboratorijske veličine
koji koristi djelomičnu reakciju nitritacije i anaerobne oksidacije amonijaka za uklanjanje
amonijaka iz otpadnih voda koji gotovo potpuno autotrofno, tj. bez potrebe za organskim
ugljikom kao ishranom za aktivne bakterije, uklanja dušik iz otpadnih voda. Pokazano je da je
taksonomski sastav bioreaktora raznolik te da se u njemu nalaze u velikom broju i heterotrofne
skupine vezane uz druge puteve mikrobnog ciklusa dušika, no da su enzimi ciljanih reakcija
(oksidacije amonijaka u nitrit i anammox reakcije) svejedno snažno eksprimirani i da je ova
metoda uklanjanja dušika iz otpadnih voda vjerojatno stabilna i s prisustvom brzo rastućih
heterotrofnih bakterija. Poželjna bi bila slična analiza ovog tipa bioreaktora, na industrijskoj
veličini i pri različitim uvjetima.Removal of various substances from wastewater before it is discharged into the environment is
necessary to ameliorate the harmful ecological effects of eutrophication on natural water bodies.
Different kinds of bioreactors are commonly used for removal of nitrogen from wastewater. In
this master thesis, the taxonomic and functional properties of a laboratory scale partial nitritationanammox bioreactor were analysed. This type of bioreactor removes nitrogen from wastewater
almost completely autotrophically, leaving much of the organic carbon present in influent
wastewater available for anaerobic digestion and biogas production. The analysis showed that the
taxonomic composition of the active microbial community is diverse and contains many
heterotrophic bacterial groups responsible for other pathways of the microbial nitrogen cycle.
Still, enzymes included in nitritation and anammox were predicted to be strongly expressed,
pointing to the stability of the partial nitritation-anammox process even with many fast-growing
heterotrophic species present. In the future, similar analyses should be done on industrial scale
bioreactors operating under variable conditions
Transfer learning of interatomic potentials: from molecules to crystals
No full textStrojno učenje ima mogućnost promijeniti paradigmu izračuna svojstava kompleksnih molekula i kristala. Dosadašnje precizne metode bazirane na teoriji funkcionala gustoće su računalno preskupe za složene zadatke kao što je predviđanje kristalnih struktura. U ovom radu je dan pregled primjene suvremenih metoda strojnog kao i dubokog učenja na problem određivanja interatomskih potencijala i sila. Osim toga, testiran je prijašnji strojno naučeni potencijal na strukturama sedmog slijepog testa predviđanja kristalnih struktura te su mu prijenosnim učenjem značajno popravljene performanse.Machine learning has the ability to change the paradigm of calculating the properties of complex molecules and crystals. Previous precise methods based on density functional theory are computationally too expensive for complex tasks such as the prediction of crystal structures. This paper provides an overview of the application of modern methods of machine as well as deep learning to the problem of determining interatomic potentials and forces. In addition, the previous machine learning potential was tested on the structures of the seventh blind prediction test of crystal structures, and its performance was significantly improved by transfer learning
The association of the global phenomenon of urban heat islands with the increase in insect populations in urban centers
No full textProces urbanizacije dovodi do fenomena zvanog „Urbani toplinski otoci“. Urbani
toplinski otoci područja su čija je prosječna temperatura zraka viša u odnosu na suburbana i
ruralna područja. Porast urbane temperature ima najizraženije učinke na ektotermne organizme
– životinje čiju tjelesnu temperatura uvjetuje okolina. Budući da su insekti vitalna komponenta
kopnene biološke raznolikosti, od presudne je važnosti spoznati skup uvjeta koje nameće
urbanizacija (klimatske promjene, dostupnost hrane, prisutnost grabežljivaca, smanjenje
staništa i dr.) te odgovor insekata na novonastale promjene. Gradovi odražavaju uvjete za koje
se smatra da će uslijed globalnog zagrijavanja, biti uvjeti većine staništa. Zbog toga gradovi
nude svojevrsnu mogućnost uvida u buduća zbivanja. Do sada je poznato da su gradska
područja obilježena smanjenom raznolikošću insekata, posebno dvokrilca (Diptera) i leptira
(Lepidoptera). U povoljnijem položaju su opnokrilci (Hymenoptera), posebice pčele
(Anthophila). One su u gradskim sredinama učinkovitije u vidu oprašivanja cvjetnica – napose
u botaničkim i stambenim vrtovima te parkovima. Urbani toplinski otoci dovode i do tzv.
„buđenja spavača“ odnosno do razvoja prilagodbi koje pojedine vrste pretvaraju u invazivne
štetnike. Povećanje topline u gradovima rezultiralo je porastom broja biljojednog štetnika
P.quercifex. Budući da je širenje gradova u nepokolebljivom zamahu, rad nastoji predvidjeti
promjene koje će se događati s populacijama insekata.The process of urbanization has led to a phenomenon referred to as "urban heat
islands". Urban heat islands are areas whose average air temperature is higher than the
temperature in suburban and rural areas. The increase in urban temperature has the most
pronounced effects on ectothermic organisms – animals whose body temperature depends on
the environment. Since insects are a vital component of terrestrial biodiversity, it is essential to
identify the set of conditions imposed by urbanization (climate change, food availability,
presence of predators, habitat reduction, etc.) and the response of insects to new changes. Cities
reflect the conditions which are expected to become the conditions of most habitats due to
global warming. As a result of this, cities provide insight into future events. Until the present
day, urban areas have been considered to contain a reduced diversity of insects, especially twowinged insects (Diptera) and butterflies (Lepidoptera). Membrane-winged insects
(Hymenoptera), especially Anthophila bees, are in a more favorable position. They are more
effective in urban areas in terms of pollination of flowering plants – especially in botanical and
residential gardens and parks. Urban heat islands also lead to the so-called "awakening of
sleeper species", i.e., to the development of adaptations that turn certain species into invasive
pests. The increase of heat in cities has resulted in an increase in the herbivorous pest
P.quercifex. Due to the burgeoning expansion of cities, the paper aims to predict the changes
that will occur to insect populations
Comparative phosphoproteome analysis of Streptomyces rimosus oxytetracycline producers strains
No full textStreptomiceti su višestanične bakterije složenog životnog ciklusa. Najpoznatije su po
genetičkom potencijalu za sintezu antibiotika širokog spektra u koje spadaju i tetraciklini od
izuzetnog komercijalnog značaja. Već desetljećima se bakterija Streptomyces rimosus koristi
za proizvodnju oksitetraciklina (OTC) čija godišnja potrošnja prelazi 108
kg. Biosinteza
antibiotika je kontrolirana kompleksnim signalnim putevima koji uključuju i fosforilacije
proteina. Kako bi rasvijetlili regulatorne mehanizme uključene u procese odgovorne za rast i
sintezu OTC-a u ovoj doktorskoj radnji je primjenom spektrometrije masa po prvi put istražen
(fosfo)proteom bakterije S. rimosus G7 i visokog proizvođača OTC-a (soj 23383). Određena
je dinamika sinteze (fosfo)proteina tijekom rasta ovih bakterija, a ostvareni rezultati su
korelirani s procesima uključenim u biosintezu antibiotika i staničnu diferencijaciju.
Identificirano je 4053 proteina (~50% proteoma) te 433 fosfoproteina od kojih je 203
fosfoproteina pronađeno samo kod soja 23383. Funkcionalna karakterizacija i analiza dinamike
fosforilacije ovih proteina dali su posve novi uvid u fosfoproteom streptomiceta općenito.
Identificirana je do sada neopisana posttranslacijska modifikacija niza proteina koji su važni
za staničnu diobu i metabolizam te sintezu antibiotika i odgovor na stres.Streptomycetes are multicellular bacteria with a complex life cycle. They are best known for
their great potential for the synthesis of broad-spectrum antibiotics, which include tetracyclines
of significant commercial importance. For decades, Streptomyces rimosus has been used to
produce oxytetracycline (OTC) whose annual consumption exceeds 108
kg. Antibiotic
biosynthesis is controlled by complex signaling pathways that include protein phosphorylation.
In order to elucidate the regulatory mechanisms involved in the processes responsible for
bacterial growth and OTC synthesis, the (phospho)proteome of S. rimosus G7 and a high OTC
producer (strain 23383) was investigated for the first time using mass spectrometry in this
doctoral dissertation. The dynamics of (phospho)proteomes during the growth of these bacteria
was determined and results were correlated with the processes involved in antibiotic
biosynthesis and cell differentiation. In total, 4053 proteins (~ 50% of proteomes) and 433
phosphoproteins were identified, of which 203 phosphoproteins were found only in strain
23383. Functional characterization and analysis of phosphorylation dynamics of these proteins
gave a completely new insight into streptomycete phosphoproteins in general. So far
undescribed posttranslational modification of a number of proteins important for cell division
and metabolism, as well as antibiotic synthesis and stress response, has been identified
Rekonstrukcija zajedničkoga pretka eukariota kladističkim i filogenetičkim pristupom
No full textOrganisation and diversity of the eukaryotic cells are well documented phenomena today, so it is already known
scientific theory that LECA (the Last Eukaryotic Common Ancestor) harboured mitochondrion, nucleus,
endoplasmic reticulum made of bacterial lipids, sex, meiosis, and eukaryotic life cycle. None of the
aforementioned traits has been found in prokaryotes. The origin of those eukaryotes traits has, on the other side,
been an unresolved issue for many years. It is questionable whether the mitochondrion (bacterial endosymbiont)
entered the archaeal host cell prior to the formation of the nucleus or later; it has never been systematically studied
if LECA had a single or many nuclei; it has not been quantified how many gene duplications there were in LECA,
and what is their origin. Furthermore, cladistic terminology is often misapplied in molecular evolution and studies
are rarely based on taxon-rich sampling, meaning that eukaryotic diversity is not well covered. This dissertation,
hence, aims to discuss cladistics and its interpretation in theory, with emphasis on the definition of eukaryotes;
and practically, by analyses, to shed some light on the genome organization, morphology, and physiology of
LECA. Eukaryotes/Eukarya are defined as a monophyletic, holophyletic group with polyphyletic, reticulated
origin. Because of the reticulated origin of eukaryotes and because mitochondria and the nucleus are not regarded
as prokaryotes anymore, both Bacteria and Archaea are paraphyletic, i.e., monophyletic groups. Many
duplications were present in LECA and the Bacteria-derived ones were found to be prevalent what suggests that
mitochondria-early hypothesis might be correct. Except for the genes that originated from plastid acquisition
(Cyanobacteria), no specific genes were found within eukaryotic supergroups, suggesting that differential loss
and genome duplications are the major forces of the eukaryotic evolution. Ubiquity of the multinucleate state
across the eukaryotic domain is presented. Traits annotated on the eukaryotic tree were multinucleate state
presence and absence, open vs. closed nuclear division, as well as 'control traits' for which it is known to be
ancestral to LECA (presence of sex, mitochondria) or for which it is known not to be ancestral to LECA (plastid,
polyploidy). Ancestral state reconstruction did not reject the hypothesis that LECA was multinucleated, similar to
modern aseptate fungi or myxomycetes, and exhibited closed nuclear division. It is confirmed (i.e., not rejected)
that LECA was sexual, had mitochondria, did not have plastid and was not polyploid. The results of ancestral state
investigations presented in this work indicate that, contrary to popular beliefs, LECA was likely not a uninucleate
cell, from which it follows that uninuclear eukaryotes possibly represent highly specialized forms, of which some,
such as Excavata might even have originated long time ago from LECA's gametes.Raznolikost eukariota i organizacija njihovih stanica danas su već dobro poznati pa se može smatrati znanstvenom
teorijom da je LECA (engl. Last Eukaryotic Common Ancestor, Posljednji zajednički predak eukariota) imao je
mitohondrij, jezgru, unutarstaničnu mrežu membrana građenu od bakterijskih lipida, spol, mejozu i eukariotski
životni ciklus. U prokariota, usporedbe radi, ne postoji ni jedno od ovih obilježja. Usprkos dobrom poznavanju
njihove građe, postanak eukariota i dalje je jedan od neriješenih problema moderne znanosti. Ne zna se je li
mitohondrij (bakterijski endosimbiont) ušao u arheju prije ili nakon formacije jezgre; nikad nije utvrđeno je li
LECA imao samo jednu ili je imao više jezgara; do sada nije određeno koliko je LECA imao dupliciranih gena i
koje im je porijeklo. Uza sve to, u molekularnoj evoluciji često se pogrešno koristi terminologija sistematike, a
radovi najčešće ne uključuju veliku raznolikost, tj. nije pokriveno mnogo svojti. Ciljevi ove disertacije jesu
teoretski raspraviti terminologiju sistematike i njezinu interpretaciju, s naglaskom na definiciju eukariota; kao i
istražiti organizaciju genoma, morfologiju i fiziologiju LECA-e praktičnim analizama. Eukarioti
(Eukaryota/Eukarya) su definirani kao monofiletska; holofiletska skupina polifiletskog postanka. Zbog hibridnog
postanka eukariota i budući da se mitohondrij i jezgra više ne smatraju prokariotima, i bakterije (Bacteria) i arheje
(Archaea) su parafiletske tj. monofiletske skupine. Otkriveno je da je LECA imala mnogo duplikacija i da je
najviše onih koje potječu od bakterija što ide u prilog hipotezi da je mitohondrij bio prisutan tijekom same
eukariogeneze. Osim plastidnih gena koji su porijeklom iz cijanobakterija (Cyanobacteria), nisu pronađeni
jedinstveni geni niti u jednoj supergrupi što znači da su veliki gubitci dijelova genoma i duplikacije gena glavne
sile evolucije eukariotskog genoma. Višejezgrene stanice su učestale među eukariotima i u disertaciji je prikazana
njihova raznolikost. Na stablu eukariota označene su prisutnost i odsutnost višejezgrenih stanica te otvorena i
zatvorena dioba jezgre, kao i „kontrolna svojstva“, tj. ona za koja se zna da li su predačka LECA-i (spol,
mitohondrij) i ona za koja se zna da nisu (plastid, poliploidija). Rekonstrukcija predačkih svojstava nije odbacila
pretpostavke da je LECA bila višejezgrena, vjerojatno slična današnjim aseptičnim gljivama i sluznjačama
(Myxomycetes), kao ni da je imala zatvorenu diobu jezgri. Potvrđeno je također, tj. nije odbačeno, da je LECA
bila spolni organizam, da je imala mitohondrije, da nije imala plastide i da nije bila poliploidna. Suprotno
uvriježenom mišljenju, LECA najvjerojatnije nije bila jednojezgreni organizam i prema tome jednojezgreni
jednostanični eukarioti vjerojatno predstavljaju visokospecijalizirane organizme, od kojih neki poput supergrupe
Excavata—smisleno nagađanje—možda čak potječu od LECA-inih gameta
Organocatalytic stereoselective synthesis of isoindolinone derivatives with triaryl substituted quaternary stereogenic center
No full textU sklopu ove doktorske radnje razvijen je protokol koji opisuje sintezu derivata izoindolinona s triaril-supstituiranim kvaternim stereogenim centrom u organokatalitičkim uvjetima. Provedeno je stereoselektivno i regioselektivno ariliranje izoindolinona, te aza-Friedel Craftsova adicija pirola kroz položaj C3. Tako opisane transformacije katalizirane kiralnim fosfornim kiselinama uključuju širok raspon različitih nukleofila i izoindolinonskih alkohola za stvaranje kvaternog stereogenog centra s tri arilna supstituenta u odličnim prinosima i razinama enantioselektivnosti (do 98% prinosa, do 99,5:0,5 e.r.). Mehanizam stereokemijske indukcije predložen je na temelju rezultata dobivenih kvantno-mehaničkim računima i kontrolnim eksperimentima. Ispitana je primjenjivost opisanih metodologija provedbom reakcije na većoj skali i posttransformacijskom reakcijom bez gubitka optičke čistoće.An organocatalytic asymmetric protocol for the synthesis of isoindolione derivatives possessing triaryl-substituted quaternary stereogenic centers is developed. Stereoselective and regioselective arylation of isoindolinones with phenols and pyrroles at C3 position has been carried out. Described stereoselective transformations proceed smoothly with a broad range of arenes and isoindolinone alcohols in reactions mediated by chiral phosphoric acid catalyst to generate triaryl-substituted quaternary stereogenic centers in excellent yields and enantioselectivities (up to 98% yield, up to 99,5:0,5 e.r.). In the order to shed light on the mechanism of stereochemical induction, control experiments and density functional theory calculations have been performed. Applicability of such described methodologies has been investigated by conducting the postmodification and scale-up reaction without loss of optical purity in the products
Lokalizacija auksina i proteina PIN tijekom somatske embriogeneze vrste Brachypodium distachyon
No full textBrachypodium distachyon is a model species used for research of Poaceae. The phylogenetic
link this species shares with monocots of agronomic importance makes it the ideal model for
studying developmental mechanism with economic applications, like somatic embryogenesis
(SE). As auxin plays a critical role in SE, tracking its presence during SE enables description
of the process as a whole. For this purpose, fluorescently-tagged PIN-FORMED (PIN) auxin
transporters and presence of auxin was examined using confocal microscopy. Findings
confirmed PIN1a to be a major marker of SE as it is expressed in all stages of SE and revealed
the complementary but mutually exclusive distribution patterns of SoPIN1 and PIN1b.
Moreover, examinations of markers of auxin presence revealed how SoPIN1 and PIN1b affect
its flow and thus influence SE. Additionally, with the goal of furthering understanding of the
effect these select PIN auxin transporters have on SE, response of loss-of-function mutants
pin1a, pin1b and their cross pin1a × pin1b to in vitro SE induction was compared using
PAS/NBB staining. Results have shown no identifiable histological differences in comparison
to wild-type explants, hinting at functional redundancy of the remaining PIN transporters
allowing SE to occur.Brachypodium distachyon je vrsta koja se koristi pri proučavanju porodice Poaceae. Njena
filogenetska povezanost s jednosupnicama od agronomske važnosti čini je idealnom za
proučavanje razvojnih mehanizama s ekonomskim primjenama, poput somatske embriogeneze
(SE). Kako auksin ima ključnu ulogu u SE, praćenje njegove prisutnosti tijekom SE omogućava
opisivanje tog procesa u cjelini. U tu svrhu, odabrani su fluorescentno označeni transporteri
auksina PIN-FORMED (PIN) za prisutnost auksina te proučeni pomoću konfokalnog
mikroskopa ili konfokalne mikroskopije. Rezultati su pokazali da je PIN1a važan marker SE
budući da je eksprimiran tijekom svih stadija SE te da su obrasci distribucije SoPIN1 i PIN1b
komplementarni i međusobno isključivi. Štoviše, proučavanje markera prisutnosti auksina
pokazalo je na koji način SoPIN1 i PIN1b utječu na njegov tok i time oblikuju SE. Uz navedeno
je proučen učinak odabranih PIN auksinskih transportera na proces SE, uspoređujući odgovor
loss-of-function mutanta pin1a, pin1b te njihovog križanca pin1a × pin1b na indukciju SE in
vitro koristeći se bojanjem PAS/NBB. Histološke razlike mutanata i eksplantanata divljeg tipa
nisu utvrđene, što ukazuje kako funkcionalna redundantnost preostalih proteina PIN
omogućava odvijanje SE
Ferrocene as a chiroptical sensor for determining the chirality of amino acids and peptides
No full textU radu je provedena konformacijska analiza i karakterizacija obrazaca vodikovih veza na
odabranim skupovima monosupstituiranih ferocenskih peptidomimetika hijerarhijskim
pristupom odnosno kombinacijom molekulsko- i kvantno-mehaničkih metoda. Računalno
dobiveni rezultati uspoređeni su s eksperimentalnim podacima. Računalnom kemijom utvrđeno
je da središnja kiralnost aminokiseline i/ili helična kiralnost kratkog peptidnog lanca izravno ili
preko kratke akiralne poveznice vezanih na ferocensku skupinu utječu na predznak
apsorpcijskog maksimuma ferocenskog kromofora (oko 470 nm) u spektru cirkularnog
dikroizma. Predznak i veličina Cottonovog efekta u korelaciji su s predznakom i veličinom
diedarskog kuta χ kojim je opisana rotacija amidne skupine izravno vezane na ferocenski
ciklopentadienilni prsten. Uvođenje akiralnih aminokiselina, poput 2-amino-2-metilpropanske
kiseline (Aib) i 1-aminocikloheksankarboksilne kiseline (Ac6c), stvaranjem β-okreta i 310
uzvojnica vodi k većoj zastupljenosti jednog od konformera u Boltzmannovoj raspodjeli pri
298 K. Navedeno bi se moglo iskoristiti u dizajnu nove skupine selektivnih kirooptičkih senzora
temeljenih na ferocenskom kromoforu za određivanje središnje kiralnosti aminokiselina i
helične kiralnosti kratkih peptidnih lanaca.n this thesis conformational analysis and characterization of hydrogen bond patterns were
performed using a hierarchical approach combining molecular and quantum mechanics
methods on selected groups of monosubstituted ferrocene peptidomimetics. The computational
results were compared with experimental data. Computational chemistry confirmed the central
chirality of the amino acid and/or the helical chirality of the short peptide chain, directly or via
a short achiral linker attached to the ferrocene group, affect the sign of the absorption maximum
of the ferrocene chromophore (at 470 nm) in the circular dichroism spectrum. The sign and
magnitude of the Cotton effect correlates with the sign and magnitude of the dihedral angle χ
describing the rotation of the amide group directly attached to the cyclopentadienyl ring of
ferrocene. The introduction of achiral amino acids, such as 2-amino-2-methylpropanoic acid
and 1-aminocyclohexanecarboxylic acid, through the formation of β-turns and 310 helices,
results in a greater prevalence of a single conformer in the Boltzmann distribution at 298 K.
This information could be used in the development of a new group of selective chiroptical
sensors based on ferrocene chromophores to determine the central chirality of amino acids and
the helical chirality of short peptide chains