Creatine kinase affinity labeling

In the course of studying the mechanism of action of creatine kinase from rabbit skeletal muscle (M.M isoenzyme), Kenyon and coworkers (4,90) have been involved in the design of specific irreversible inhibitors that are active-site-directed (affinity labels). Creatine kinase catalyzes the reversible transfer of a phosphoryl group ( the elements of "POi") from ATP to creatine, as shown in the following reaction ... 

A good example of an affinity label for creatine kinase has been presented (35). This enzyme catalyzes the reversible transfer of a phosphoryl group from adenosine triphosphate [56-65-5] (17) to creatine [57-00-1] (18), leading to adenosine diphosphate [7584-99-8] (19) and phosphocreatine [67-07-2]... 

A/-(2,3-Epoxypropyl)-A/-amidinoglycine [70363-44-9] (21) was shown to be an affinity label of creatine kinase. Its mechanism of covalent bond formation is outlined as follows ... 

General aspects of enzymatic reactions cateuLyzed by kinases are briefly mentioned. Many alternate substrates, competitive inhibitors and affinity labels based either on the structure of ATP or on the structure of the non-ATP kinase substrates are described. Several examples are presented that should be of particular interest to the medicinal chemist. Finally, the design of an affinity label for creatine kinase is reviewed as an example of how such information can be used in the search for agents directed at an enzyme s active site. 

Designing specific enzyme inhibitors on a rational basis when one does not have a detailed three-dimensional crystal structure to which to relate is a rather sophisticated challenge. Some viable approaches to such a challenge are discussed in a review chapter by Santi and Kenyon (91) This discussion will focus on our rationale for the design of an affinity label for creatine kinase, namely N-(2,3-epoxypropyl)-N-amidinoglycine (epoxycreatine ) ... 

Exploration of Bulk Tolerance. Most affinity labels contain functional groups added to the substrate s basic structure. Discerning just where added bulk can be tolerated by the enzyme is therefore crucial information. In the case of creatine, it has been determined (92,93) that the structures below, for example, are good substitutes for creatine in the creatine-kinase reaction... 

Affinity labeling ATP sites, 194-96 creatine kinase, 200-205 Amastatin, 94-96 Amide bond hydrolysis, 227 Amino acid sequences, renin inhibitors, 139,141f D-Amlno acids and activity,... 

Creatine kinase - [MEDICALDIAGNOSTIC REAGENTS] (Vol 16) -affinity label for [ENZYME INHIBITORS] (Vol 9)... 

Buechter, D. D. Affinity Labeling of Creatine Kinase, PhD Thesis University of CaUfomia San Francisco, CA, 1990. 

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