Affinity-labeling studies

Some information concerning the stereochemical orientation of active site residues in the solution state has been obtained by affinity labeling studies using broinoacetamidophenyl (69) and diazoniuin (70) derivatives of p-aminophenylnucleotide inhibitors,... 

Affinity Labeling Studies an Myeloma Proteins and Antibodies... 

Chen, R. W., Wagner, P. A., Hoekstra, W. G., and Ganther, H. E., 1974b, Affinity labeling studies with ° Cadmium in cadmium-induced testicular injury in rats, J. Reprod. Pert. 38 293. 

In view of the crucial metabolic role played by ribulosebisphosphate carboxylase and the ease with which this enzyme can be isolated (it constitutes about 16% of the total protein in spinach leaf"), it is not surprising that a multitude of studies have been reported concerning its isolation, chemical and physical characterization, mechanism of action, and mode of regulation. Excellent reviews on these topics arc available, and no attempt to duplicate or summarize them will be made here. However, properties of the enzyme that are pertinent to affinity labeling studies will be described briefly. 

As is obvious, we have primarily relied on bromoacetoxy and bromo-acetamido derivatives in our affinity-labeling studies. These compounds are reasonably stable, yet possess considerable reactivity with nucleophilic groups commonly found in amino acid side chains. The chloro-acetoxy derivatives, on the other hand, are reasonably unreactive, and iodoacetoxy derivatives lack the stability of the bromoacetoxy compounds. 

Reagents. Modified and unmodified antibiotics employed in reported affinity labeling studies are listed in Table IV. " The synthesis of additional derivatives of chloramphenicol of potential use in photoaffinity labeling has been described. Interestingly, the list includes two unmodified antibiotics chloramphenicol and puromycin. These two as well as reagents e and i react with the ribosome photolytically. 

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