Role of enzyme-peptide substrate backbone hydrogen bonding in determining protein kinase substrate specificities.
As part of a search for peptides that have specificity for selected protein kinases, the possibility that adenosine cyclic 3',5'-phosphate dependent protein kinase (A-kinase) recognizes the hydrogen-bonding potential of its peptide substrates was investigated. A-Kinase catalyzes the phosphorylation of five N alpha-methylated and four depsipeptide derivatives of Leu-Arg-Arg-Ala-Ser-Leu-Gly (peptide 1) at rates that differ by at least 7 orders of magnitude. These peptide 1 analogues each lack the ability to donate a hydrogen bond at selected positions in the peptide chain. If a particular amide hydrogen of a peptide amide is involved in hydrogen bonding, which is important for enzyme recognition, the prediction is that peptides which contain an ester or a N-methylated bond at that position in peptide 1 will be comparatively poor substrates. In contrast, if a depsipeptide has a reactivity comparable to that of peptide 1 but the analogous N-methylated peptide has a poor reactivity with A-kinase, the result might indicate that the N-methyl group causes unfavorable steric effects. The depsipeptide that lacks a Leu6 amide proton is a good substrate for A-kinase, but the corresponding N-methylated peptide is phosphorylated far less efficiently. This result and others presented in this paper suggest that although enzyme-substrate hydrogen bonding may play some role in A-kinase catalysis of phosphoryl group transfer, other explanations are necessary to account for the relative reactivities of N alpha-methylated and depsi-containing peptide 1 analogues.(ABSTRACT TRUNCATED AT 250 WORDS)
Thomas
N E
NE
Laboratory of Bioorganic Chemistry and Biochemistry, Rockefeller University, New York, New York 10021.
Bramson
H N
HN
Miller
W T
WT
Kaiser
E T
ET
D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D006860:Hydrogen Bonding; D007700:Kinetics; D046911:Macromolecular Substances; D009206:Myocardium / Q000201:enzymology; D011485:Protein Binding; D011494:Protein Kinases / Q000378:metabolism*; D013379:Substrate Specificity
D046911:Macromolecular Substances; D011494:Protein Kinases