A few week ago, Alex Bell asked for information about non-disulfide cross-links between proteins. The replies, shown below, seemed to involve cross-links occuring naturally in biological systems, although I haven't examined all the references. I would like to reopen this question for cross-links formed under degradative conditions.
For instance, disulfides can degrade by beta-elimination in alkaline solutions (or at pHs 6-8 at 90-100C) to form dehydroalanine. The electrophilic dehydroalanine can then react with the amino group of lysine or the thiol of cysteine, forming a covalent cross-link. (See "Disulfide Bonds in Proteins" by PA Kosen, in "Stability of Protein Pharmaceuticals, Part A", Ed. TJ Ahern &MC Manning, 1992)
Are there other well-defined cross-links formed under degradative conditions? I'd be especially interested in hearing about those involving oxidative or free-radical mechanisms.
Vernon
Vernon A. Shoup
Regeneron Pharmaceuticals, Inc.
Rensselaer, NY 12144
(518)488-6012
vernon.shoup@regpha.com
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Date: 04/28/1999 2:49 PM
From: Elizabeth Fowler
Analytical methods for the collagen cross-links are described in Saito et
al., Analytical Biochemistry 253:26-32 (1997) and Muller et al., Rheumatol.
Int. 16: 23-28 (1996). Vol 82 of Methods of Enzymology has a couple of
chapters describing the formation of these cross-links.
Beth Fowler
At 12:48 PM 4/27/1999 -0400, John Hempel wrote:
>At 10:50 AM 4/26/99 -0400, alex bell wrote:
>I am interested in getting any information regarding NON-disulfide
>covalent-crosslinking of proteins.
> >Thanks in advance,
> alex >Dept Anat & Cell Biol, McGill University, Montreal
>
>Alex:
>
>Assuming that you are only interested in amino acid-to-amino acid links,
>here is a non-exhaustive list of refs to odd x-links (additions welcome!!): >
>Ser-to-His: Biochemistry (1986) 25: 2392-96 (aka histidinoalanine)
>
>Cys-to-His: JBC (1982) 257: 6414
>
>Trp-to-Trp: Science (1991) 252: 817
>
>Cys-to-Tyr: Nature (1991) 350:87 >
>Cys-to-Trp: Naturwissenschaften (1987) 74: 367-373 (aka tryptathionine,
>not cystophan as we called it here before finding it had already been
>discovered - !@$%!!)
>
>Lys-to-Tyr: Science (1996) (for some reason I've lost the volume to this
>ref, but the page is 1078; author is SF Wang
>
>Then there are a variety of isopeptide (Lys-to-Asp/Asn/Glu/Gln) links which
>are known.
>
>Some of the above can be found in Meth Enzymol vols 106&107, see esp 106:
>351 (H/S) & 355 (H/C), 107: 241 & 258 (isopeptides links), 377 &388
>(dityrosine) >
>Then, perhaps the most amazing, although mayve not a crosslink in the sense
>that the residues are sequentially adjacent, is the one involving the
>Ser-Tyr-Gly tripeptide that forms the fluorophore in the central helix of
>green fluorescent protein. The whole protein is fascinating as well. The
>central helix is surrounded by an 11-stranded beta-barrel (aka "green
>lantern structure": B-C Wang's terminology) See Science (1996) 273:1392,
>and also a great review article in Ann Rev Biochem (1998) 67:509-44.
>
>Then, there are Lys/Lys ones in connective tissues like lysinorleucine and
>desmosine that are covered in textbooks like Stryer. >
>Also a good one in collagen which ought to be included on this list too -
>the crosslink remains after proteolysis and is excreted. This forms the
>basis of an apparently highly accurate test for osteoporosis, but I'm
>lacking a good ref for that at the moment. >John Hempel, PhD Ph (412) 624 0161
>University of Pittsburgh FAX (412) 624 4759
>Department of Biological Sciences
>Pittsburgh PA 15260 email: hempel@psc.edu
> http://www.pitt.edu/~biology/faculty/hempel.html