collagen peptides, prolyl-hydroxyproline, aspartate transaminase (AST) - brief notes

Marine collagen peptides have antioxidant properties. 

Characterization and Antioxidant Activity of Collagen, Gelatin, and the Derived Peptides from Yellowfin Tuna (Thunnus albacares) Skin [2020] - https://pubmed.ncbi.nlm.nih.gov/32023998/ 

Functional and bioactive properties of collagen and gelatin from alternative sources: A review [2011] - https://www.sciencedirect.com/science/article/pii/S0268005X11000427

"The exact mechanism underlying the antioxidant activity of peptides is not fully understood, but various studies have shown that they are lipid peroxidation inhibitors, free radical scavengers and transition metal ion chelators. According to some studies, gelatin peptides could inhibit lipid peroxidation more efficiently than antioxidative peptides derived from many other protein sources ...

  .. peptides isolated from hoki skin gelatin were capable of enhancing the expression of antioxidative enzymes such as glutathione peroxidase, catalase and superoxide dismutase in human hepatoma cells ... "


Hepatoprotective Effect of Collagen Peptides From Cod Skin Against Liver Oxidative Damage In Vitro and In Vivo [2014] - https://link.springer.com/article/10.1007%2Fs12013-014-0313-x

"Furthermore, CSCP [cod skin collagen peptides ] pulled down serum ALT and AST level, increased the activities of SOD and CAT, and decreased MDA in both murine models of acute liver toxicity. Pretreatment with CSCP protected liver tissue against oxidative injure in vivo and in vitro. The underlying mechanism might involve enhancement in the activities of antioxidant enzymes and reduction in the lipid peroxidation."

I decided against supplementing with marine collagen peptides (derived from fish skins) due to concerns over possibility of BMAA contamination.It seems possible since shark cartilage has been found to be contaminated with BMAA. https://pubmed.ncbi.nlm.nih.gov/24755394/

 Collagen peptides from other sources may have similar antioxidant effects, but it there are a number of papers on marine collagen peptides since fish skins are an abundant waste product. Glycine and prolyl-hydroxyproline have also been reported to have antioxidant, hepatoprotective  and anti-inflammatory effects, and both are available in collagen from other sources.

Effect of Glycine on Lead Mobilization, Lead-Induced Oxidative Stress, and Hepatic Toxicity in Rats [2011] - https://www.hindawi.com/journals/jt/2011/430539/
  

Collagen Hydrolysate Corrects Anemia in Chronic Kidney Disease via Anti-Inflammatory Renoprotection and HIF-2α-Dependent Erythropoietin and Hepcidin Regulation [2020] - https://pubmed.ncbi.nlm.nih.gov/32981311/

"Prolyl-hydroxyproline exerted direct anti-inflammatory effects on lipopolysaccharide-activated macrophages and elicited stimulating and inhibiting activities on erythropoietin expression and hepcidin overproduction, respectively, in HepG2 cells by HIF-2α activation. Overall, CH [collagen hydrosylate] was effective in correcting renal anemia via anti-inflammatory renoprotection and HIF-2α-dependent erythropoietin and hepcidin regulation." 

Prolyl-hydroxyproline, a collagen-derived dipeptide, enhances hippocampal cell proliferation, which leads to antidepressant-like effects in mice [2020] - https://faseb.onlinelibrary.wiley.com/doi/10.1096/fj.201902871R 

"PO [prolyl-hydroxyproline] significantly increased the gene expression of brain-derived neurotrophic factor [BDNF] and nerve growth factor [NGF] in the hippocampus, and promoted the proliferation of neural progenitor cells in vivo and in vitro. PO also increased the dopamine concentration in the prefrontal cortex. Thus, PO-dependent regulation of neurotrophic function and neurotransmitter may be the mechanism for antidepressant-like behavior."

  ~

Somehow I got onto the preceding topic after coming across  this article on the kinetics of aspartate transaminase [aspartate aminotransferase, AST]. 


Kinetics of soluble and collagen-bound aspartate aminotransferase: diffusional effects with a two-substrate enzymatic reaction [1977] - https://www.jbc.org/article/S0021-9258(17)40911-2/fulltext

"The kinetic properties of aspartate aminotransferase covalently bound to collagen are compared to those of the free enzyme. In the bound state, the enzyme exhibits a greater affinity for glutamate, but a lower affinity for oxalacetate [oxaloacetate]."


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