1,720,977 research outputs found
A signature protein-based method to distinguish Mediterranean water buffalo and foreign breed milk.
No full textA novel genetic variant at the as1-casein locus of water buffalo (WB), 8-residue shorter than its wild-type
has been found and sequenced. The internal deletion of the peptide E35KVNELsT42 was confirmed by the
isolation of the junction peptide. The 8-residue deletion mutant has a molecular weight that is 919 Da
less than that of the wild-type. The novel isoform with a unique f35-42 deletion could be the result of
the skipping of exon 6, generating an exon 6-deleted variant of as1-casein. The wild-type and its shortened
as1-casein forms were found to co-exist in many individual milk samples. In contrast, the 8-residue,
internally deleted as1-casein variant did not occur in water buffaloes of the Mediterranean breed reared
in Italy. Wild-type as1-casein has 6 to 8 phosphate groups (P) while the internally deleted form 6 and 7P
per molecule
Characterisation of the heterogeneity of ovine deleted variant alphaS1-casein E by a proteomic approach
No full textThe micro-heterogeneity of the ovine αs1-CN E variant, occurring in Leccese ewe milk, was characterized using a bottom-up, shotgun proteomic approach by means of two-dimensional gel electrophoresis (2-DE) and RP-HPLC as separation techniques and polyclonal antibodies against αs1-CN and nano-liquid chromatography-electrospray ionization-time-of-flight tandem mass spectrometry nESI-QTOF/MS/MS as an identification methodology. Comparing results with the most common genetic variant αs1-CN C, αs1-CN E variant showed a reduced number of phosphorylated serine residues (αs1-CN E -4P vs αs1-CN C -9P) and a lower measured molecular weight (MW) (22241.7Da vs 23481.5Da). The MS analysis of protein tryptic digest ascertained that these differences were due to the αs1-CN (70-77) amino acid sequence deletion, coded by exon 10, thus triggering the phosphate loss on serine residues located at positions 64, 66, 68 and 75.
The loss of four phosphate groups, associated with the lower content of αs1-CN E, could be negatively related both to cheese-making aptitude of milk and mineral carrier activity
Identification of casein peptides in plasma of subjects after a cheese-enriched diet
No full textDespite several studies support the functionality of casein peptides in vitro, a gap of knowledge still exist about their bioavailability.
BIOACTIVE PEPTIDES; MASS-SPECTROMETRY; HEALTH-BENEFITS; BETA-CASEIN; PHOSPHOPEPTIDE; DIGESTION; MILKIn this pilot study the bioavailability of phosphopeptides (CPPs) was investigated in four healthy subjects who consumed for one week 100 g/day of Parmigiano Reggiano cheese after one week of a dairy products-free diet. CPPs were detected in plasma samples from fasting subjects after the cheese-enriched diet and peptides were detected variously in almost all the 4 samples. Some alpha(s1)- and alpha(s2)-CN-derived CPPs, such as alpha(s1)-CN (f43-52 and f43-50) and alpha(s2)-CN (f8-12), (f7-12) and (f6-12) as well as four non-phosphorylated peptides belonging to the C-terminal end of beta-CN (f193-209, f194-209, f200-209) were detected in plasma samples submitted to extraction and enrichment by hydroxyapatite (HA) chromatography followed by MALDI-TOF and nano LC-ESI/MS/MS analysis.
Data indicated that casein oligopeptides are bioavailable after a continued intake of cheese. Future studies are warranted to ascertain this finding on a wider population and to clarify the mechanisms behind CPPs bioaccessibility and absorption
Water buffalo s1–CN polymorphism determination by immunoelectrophoretic technique and LC/ESI/MS analysis.
No full textHydroxyapatite as a concentrating probe for phosphoproteomic analyses.
No full textA novel method for the selective enrichment of casein phosphoproteins/phosphopeptides (CPP) from
complex mixtures is reported herein. This method employs ceramic hydroxyapatite (HA) as a solid-phase
adsorbent to efficiently capture phosphoproteins and CPP from complex media. Casein was chosen as
the model phosphoprotein to test the protocol. CPP immobilized on HA microgranules formed a complex
that was included in the matrix-assisted laser desorption/ionization mass spectrometry (MALDI)
matrix before desorbing directly from the well plate. Casein fractions with different levels of phosphorylation
were desorbed based upon the specific concentration of trifluoroacetic acid (TFA) included in
the MALDI matrix. The HA-bound casein enzymolysis was performed in situ with trypsin to remove nonphosphorylated
peptides and isolate the immobilized CPP. The latter were recovered by centrifugation,
dried, and co-crystallized with a 1% phosphoric acid (PA) solution in the matrix that was appropriate for
detecting CPP in MALDI-MS spectra. This approach for the selection of casein/CPP resulted in the identification
of 32 CPP by MALDI-time of flight (TOF). The analytical process involved two steps requiring
∼2 h, excluding the time required for the enzymatic reaction. The alkaline phosphatase (AP)-assisted
de-phosphorylation of tryptic CPP allowed the phosphorylation level of peptides to be calculated concurrently
with MALDI-TOF MS and liquid chromatography-electrospray ionization–mass spectrometry
(LC–ESI–MS/MS). The effectiveness of the extraction procedure assayed on eggshell phosphoproteins
resulted in the identification of 5 phosphoproteins and 14 derived phosphopeptides with a phosphoprotein
global recovery of ∼70% at least
Characterization of goat alphas2–CN by electrophoretic techniques and mass spectrometry analysis
No full text
Ex vivo degradation of β-Casomorphin-7 by human plasma peptidases: Potential implications for peptide systemic effects
No full textPeptides surviving the simulated gastrointestinal digestion of milk proteins: biological and toxicological implications
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