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Chem. Rev. 1998, 98, 10451065

1045

Ribonuclease A

Ronald T. Raines

Departments of Biochemistry and Chemistry, University of WisconsinsMadison, Madison, Wisconsin 53706

Received October 10, 1997 (Revised Manuscript Received January 12, 1998)

Contents

A. S-ProteinS-Peptide Interaction

1058

B. New Technology

1058

I. Introduction II. Heterologous Production III. Structure IV. Folding and Stability A. Disulfide Bond Formation B. Prolyl Peptide Bond Isomerization V. RNA Binding A. Subsites B. Substrate Specificity C. One-Dimensional Diffusion D. Processive Catalysis VI. Substrates VII. Inhibitors VIII. Reaction Mechanism A. His12 and His119 B. Lys41 C. Asp121 D. Gln11 IX. Reaction Energetics A. Transphosphorylation versus Hydrolysis B. Rate Enhancement X. Ribonuclease S

1045 1046 1046 1047 1047 1048 1048 1048 1049 1049 1050 1050 1051 1052 1053 1054 1055 1056 1056 1056 1057 1058

XI. Molecular Evolution XII. Unusual Homologues XIII. Conclusion XIV. Acknowledgments XV. References

1059 1059 1060 1060 1060

I. Introduction

Biological information is stored by DNA and mani- fested by proteins. RNA serves as the conduit: 1

DNA a RNA f protein

(1)

The flow of information through RNA is essential for known life. By catalyzing the synthesis or degrada- tion of RNA, two classes of enzymes control this flow. RNA synthesis is catalyzed by RNA polymerases. RNA degradation is catalyzed by RNA depolymeras- es, which are most often called “ribonucleases”.

The ribonucleolytic activity in the pancreas of ruminants is particularly high, perhaps to digest the large amount of RNA produced by stomach microor- ganisms.2 This high level of activity has led to the

Ronald T. Raines was born in 1958 in Montclair, NJ. He received Sc.B. degrees in chemistry and biology from the Massachusetts Institute of Technology. At M.I.T., he worked with Christopher T. Walsh to reveal the reaction mechanisms of pyridoxal 5-phosphate-dependent enzymes. Raines was a National Institutes of Health predoctoral fellow in the chemistry department at Harvard University. There, he worked with Jeremy R. Knowles to elucidate the reaction energetics of triosephosphate isomerase. Raines was a Helen Hay Whitney postdoctoral fellow in the biochemistry and biophysics department at the University of California, San Francisco. At U.C.S.F., he worked with William J. Rutter to clone, express, and mutate the cDNA that codes for ribonuclease A. Raines then joined the faculty of the biochemistry department at the University of WisconinsMadison, where he is now associate professor of biochem- istry and chemistry. His honors include the 1998 Pfizer Award in Enzyme Chemistry from the American Chemical Society. His research group uses techniques that span the chemistrybiology interface to reveal protein structurefunction relationships in vitro and in vivo.

discovery3 and detailed characterization of bovine pancreatic ribonuclease A (RNase A; EC 3.1.27.5). The “A” refers to the predominant form of the enzyme in the pancreas of Bos taurus. RNase A is unmodi- fied, whereas RNase B is a mixture of glycoforms in which Man5-9GlcNAc2 is attached to the side-chain nitrogen of Asn34.4-6 RNase C and RNase D are still less abundant in the bovine pancreas and more heterogeneous in their glycosylation.7,8

RNase A has been the object of landmark work on the folding, stability, and chemistry of proteins; in enzymology; and in molecular evolution. Recognition of the historic role of RNase A culminated in 1972 when three researchers were awarded with the Nobel Prize in chemistry for work on this enzyme (Table 19-11). A fourth researcher was honored in 1984.

Researchers continue to choose RNase A as a model system, requiring the frequent compilation of infor- mation. Comprehensive books have appeared on nucleases12,13 and ribonucleases.14 In addition, au-

S0009-2665(96)00427-X CCC: $30.00

© 1998 American Chemical Society

Published on Web 04/07/1998

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