Abstract：
:At pH 8.9 and 37 degrees C the half-times for tritium exchange with the C-2 protons of the histidines of trypsin are 73 days for His-57, and greater than 1000 days for His-40 and His-91. These half-times are much longer than the half-life of exchange for the C-2 proton of free histidine (2.8 days at pD 8.2), and longer than any previously reported half-time of exchange at pH greater than 8. These very low rates of exchange are discussed with reference to the refined structure of trypsin. The tritium exchange of His-57 depends on an apparent pKa of 6.6. This pKa may represent the pKa of the imidazole of His-57 in an inactive conformation of the enzyme.
journal_name
Biochemistryjournal_title
Biochemistryauthors
Krieger M,Koeppe RE 2nd,Stroud RMdoi
10.1021/bi00661a010subject
Has Abstractpub_date
1976-08-10 00:00:00pages
3458-64issue
16eissn
0006-2960issn
1520-4995journal_volume
15pub_type
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