Trypsin in human milk

The Journal of Nutrition

Smink

Robinson

et al. 2015

Section: Figurementioning

confidence: 98%

Endogenous Human Milk Peptide Release Is Greater after Preterm Birth than Term Birth

The Journal of Nutrition

Smink

Robinson

et al. 2015

“…This milk trypsin, sometimes referred to as anionic trypsin, was detected in human milk by immunodiffusion and immunoelectrophoresis (72). When comparing the amino acid sequences of anionic trypsin with that of trypsin 1 and 2 (using BLAST in Uniprot), we found that anionic trypsin has the same sequence as trypsin 2 (anionic trypsin is likely an older name).…”

Section: Proteolytic Systems In Milkmentioning

confidence: 99%

“…When anionic trypsin (trypsin-2) is isolated from human milk, it is active (demonstrated by splitting the chromogenic substrate benzoyl-DL-arginine- p -nitroanilide) (72). However, in the context of milk, trypsin seems to have no activity (72).…”

Section: Proteolytic Systems In Milkmentioning

confidence: 99%

See 1 more Smart Citation

Proteolytic Systems in Milk: Perspectives on the Evolutionary Function within the Mammary Gland and the Infant

J Mammary Gland Biol Neoplasia

Murray

Gan

2015

100

Milk contains elements of numerous proteolytic systems (zymogens, active proteases, protease inhibitors and protease activators) produced in part from blood, in part by mammary epithelial cells and in part by immune cell secretion. Researchers have examined milk proteases for decades, as they can cause major defects in milk quality and cheese production. Most previous research has examined these proteases with the aim to eliminate or control their actions. However, our recent peptidomics research demonstrates that these milk proteases produce specific peptides in healthy milk and continue to function within the infant’s gastrointestinal tract. These findings suggest that milk proteases have an evolutionary function in aiding the infant’s digestion or releasing functional peptides. In other words, the mother provides the infant with not only dietary proteins but also the means to digest them. However, proteolysis in the milk is controlled by a balance of protease inhibitors and protease activators so that only a small portion of milk proteins are digested within the mammary gland. This regulation presents a question: If proteolysis is beneficial to the infant, what benefits are gained by preventing complete proteolysis through the presence of protease inhibitors? In addition to summarizing what is known about milk proteolytic systems, we explore possible evolutionary explanations for this proteolytic balance.

“…Peptides having termini that pass a comparison to an enzymatic specificity have their abundances added to the sum of the respective enzyme. Proteases known to be present in milk include plasmin (48), trypsin (49,50), elastase (50), cathepsin-D (51), and thrombin (39). In addition, undefined carboxy/amino peptidases have been proposed to act in milk (20).…”

Section: Nano-lc Mass Spectrometry Analysis Of Endogenous Peptides Inmentioning

confidence: 99%

Mechanistic Peptidomics: Factors That Dictate Specificity in the Formation of Endogenous Peptides in Human Milk

Guerrero

Molecular & Cellular Proteomics

Contreras

et al. 2014

An extensive mass spectrometry analysis of the human milk peptidome has revealed almost 700 endogenous peptides from 30 different proteins. Two in-house computational tools were created and used to visualize and interpret the data through both alignment of the peptide quasi-molecular ion intensities and estimation of the differential enzyme participation. These results reveal that the endogenous proteolytic activity in the mammary gland is remarkably specific and well conserved. Certain proteins-not necessarily the most abundant ones-are digested by the proteases present in milk, yielding endogenous peptides from selected regions. Our results strongly suggest that factors such as the presence of specific proteases, the position and concentration of cleavage sites, and, more important, the intrinsic disorder of segments of the protein drive this proteolytic specificity in the mammary gland. As a consequence of this selective hydrolysis, proteins that typically need to be cleaved at specific positions in order to exert their activity are properly digested, and bioactive peptides encoded in certain protein sequences are released. Proteins that must remain intact in order to maintain their activity in the mammary gland or in the neonatal gastrointestinal tract are unaffected by the hydrolytic environment present in milk. These results provide insight into the intrinsic structural mechanisms that facilitate the selectivity of the endogenous milk protease activity and might be useful to those studying the peptidomes of other biofluids. Molecular &