Indigenous Enzymes of Milk

Fox, Patrick F.

doi:10.1007/978-1-4614-4714-6_12

Cited by 30 publications

(15 citation statements)

References 399 publications

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“…PEnTab is unable to estimate the participation of exoproteases that may be present in milk. The evidence for exoproteases in milk, however, remains weak (O'Mahony, Fox, & Kelly, 2013). Additionally, as PEnTab works with a user-defined list of proteases, the presence of unspecified enzymes (i.e., bacterial enzymes) cannot be predicted.…”

Section: Resultsmentioning

confidence: 99%

Peptidomic analysis of healthy and subclinically mastitic bovine milk

Guerrero

Dallas

Contreras

et al. 2015

International Dairy Journal

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A variety of proteases release hundreds of endogenous peptide fragments from intact bovine milk proteins. Mass spectrometry-based peptidomics allows for high throughput sequence assignment of a large number of these peptides. Mastitis is known to result in increased protease activity in the mammary gland. Therefore, we hypothesized that subclinically mastitic milks would contain higher concentrations of released peptides. In this work, milks were sampled from three cows and, for each, one healthy and one subclinically mastitic teat were sampled for milk. Peptides were analyzed by nano-liquid chromatography quadrupole time of flight tandem mass spectrometry and identified with database searching. In total, 682 peptides were identified. The total number of released peptides increased 146% from healthy to subclinically mastitic milks (p < 0.05), and the total abundance of released peptides also increased significantly (p < 0.05). Bioinformatic analysis of enzyme cleavage revealed increases in activity of cathepsin D and elastase (p < 0.05) with subclinical mastitis.

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Section: Resultsmentioning

confidence: 99%

Peptidomic analysis of healthy and subclinically mastitic bovine milk

Guerrero

Dallas

Contreras

et al. 2015

International Dairy Journal

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“…Cleavage after arginine or lysine accounts for the majority of released peptides by count. Plasmin and trypsin cannot be differentiated with these methods, because both cleave after arginine or lysine; however, no evidence for trypsin in bovine milk exists 29 . Plasmin is known to be present and active in bovine milk 30 .…”

Section: Resultsmentioning

confidence: 99%

Peptidomic Profile of Milk of Holstein Cows at Peak Lactation

Dallas

Guerrero

Parker

et al. 2013

J. Agric. Food Chem.

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Bovine milk is known to contain naturally occurring peptides, but relatively few of their sequences have been determined. Human milk contains hundreds of endogenous peptides and the ensemble has been documented for antimicrobial actions. Naturally occurring peptides from bovine milk were sequenced and compared with human milk peptides. Bovine milk samples from six cows in second stage peak lactation at 78–121 days post- partum revealed 159 peptides. Most peptides (73%) were found in all six cows sampled, demonstrating the similarity of the intra-mammary peptide degradation across these cows. One peptide sequence, ALPIIQKLEPQIA from bovine perilipin 2 was identical to another found in human milk. Most peptides derived from β-casein, αs1-casein and αs2- casein. No peptides derived from abundant bovine milk proteins like lactoferrin, β- lactoglobulin and secretory immunoglobulin A. The enzymatic cleavage analysis revealed that milk proteins were degraded by plasmin, cathepsins B and D and elastase in all samples.

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“…Alpha‐amylase has been identified at high levels in mammary glands and in the milk of humans and several other species (Fox et al, ). When compared to plasma levels of α‐amylase, human milk has a much higher concentration of this enzyme, indicating that α‐amylase is actively produced in the mammary gland (O'Mahony, Fox, & Kelly, ). Since milk from human and others mammals does not contain starch, the function of mammary amylase is uncertain.…”

Section: Challenges To the Starch Digestion Hypothesis For Amy1 Cnvmentioning

confidence: 99%

Rethinking the starch digestion hypothesis for AMY1 copy number variation in humans

Fernández

Wiley

2017

American J Phys Anthropol

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Alpha-amylase exists across taxonomic kingdoms with a deep evolutionary history of gene duplications that resulted in several α-amylase paralogs. Copy number variation (CNV) in the salivary α-amylase gene (AMY1) exists in many taxa, but among primates, humans appear to have higher average AMY1 copies than nonhuman primates. Additionally, AMY1 CNV in humans has been associated with starch content of diets, and one known function of α-amylase is its involvement in starch digestion. Thus high AMY1 CNV is considered to result from selection favoring more efficient starch digestion in the Homo lineage. Here, we present several lines of evidence that challenge the hypothesis that increased AMY1 CNV is an adaptation to starch consumption. We observe that α- amylase plays a very limited role in starch digestion, with additional steps required for starch digestion and glucose metabolism. Specifically, we note that α-amylase hydrolysis only produces a minute amount of free glucose with further enzymatic digestion and glucose absorption being rate-limiting steps for glucose availability. Indeed α-amylase is nonessential for starch digestion since sucrase-isomaltase and maltase-glucoamylase can hydrolyze whole starch granules while releasing glucose. While higher AMY1 CN and CNV among human populations may result from natural selection, existing evidence does not support starch digestion as the major selective force. We report that in humans α-amylase is expressed in several other tissues where it may have potential roles of evolutionary significance.

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Indigenous Enzymes of Milk

Cited by 30 publications

References 399 publications

Peptidomic analysis of healthy and subclinically mastitic bovine milk

Peptidomic analysis of healthy and subclinically mastitic bovine milk

Peptidomic Profile of Milk of Holstein Cows at Peak Lactation

Rethinking the starch digestion hypothesis for AMY1 copy number variation in humans

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