Enzyme-substrate interaction by nuclear magnetic resonance

5052 Table I. Degree of Racemization during Peptide Bond Formation ~~~

Component activated+ For+ Ala For-L-Phe Ac-L-Ala Ac-L-Phe Bz-L-Ala Bz-L-Phe Z-Gly-L-Ala Z-Gly-L-Phe Z-Gly-Gly-L-Phe

Condensed witha,b

D-L

or

L-D

CDI

L-Phe-OMe L-Phe-OMe L- Ala-OMe L-Phe-OMe L- Ala-OMe L-Phe-OMe L- Ala-OMe L-Ala-OMe

~

~~~

Methyl ---resonanced-

in product with coupling agentC K DCC EDC

16