Histidine, oxidative damage

There has been a strong but very selective interest in CIDNP on amino acids, strong because of the importance for the application of CIDNP to proteins (see Section 6.9), and very selective because only three amino acids (tr)q)tophan 10, tyrosine 11, and histidine 12, compare Chart 12 for their CIDNP spectra, see Ref. 185) are routinely useable for that purpose while two others, cysteine 13 and methionine 14, have received attention because of their putative role for long-range electron transfer across cell membranes or oxidative damage of cell components. 

Toxic and carcinogenic effects of nickel compounds are associated with nickel-mediated oxidative damage to DNA and proteins and to inhibition of cellular antioxidant defenses. Most authorities agree that albumin is the main transport protein for nickel in humans and animals and that nickel is also found in nickeloplasmin - a nickel-containing alpha-macroglobulin - and in an ultrafilterable semm fraction similar to a nickel-histidine complex. Normal routes of nickel intake for humans and animals are ingestion, inhalation, and... 

Retsky, K. L., Chen, K., and Frei, B., unpublished observation). Such limited, site-specific oxidative damage to the histidine residues of apo B would result in loss of their ability to bind metal ions (Uchida and Kawakishi, 1990) and, hence, to support initiation of LDL oxidation (Retsky and Frei, 1995). Thus, vitamin C may slow the progression of atherosclerosis by inhibiting oxidative modification of LDL in vivo, irrespective of whether the mechanism is metal ion-dependent or independent. 

As for linen and other natural fibres, silk is sensitive to a variety of environmentally driven degradative processes, though in most cases the actual damage is caused by hydrolysis and/or oxidation. Attack on the polymer chains is generally initiated in the amorphous zones as a consequence of their more open structure and the incidence of reactive amino-acids (specifically histidine, lysine, phenylalanine, proline, threonine, tryptophan, tyrosine and valine). 

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