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Natural abundance 15 N NMR assignments delineate structural differences between intact and reactive‐site hydrolyzed Cucurbita maxima trypsin inhibitor III
Author(s) -
Krishnamoorthi Ramaswamy,
Nemmers Sylvia,
Tobias Brian
Publication year - 1992
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(92)80607-i
Subject(s) - heteronuclear molecule , chemistry , cucurbita maxima , chemical shift , nuclear magnetic resonance spectroscopy , stereochemistry , heteronuclear single quantum coherence spectroscopy , molecule , hydrolysis , trypsin inhibitor , amide , carbon 13 nmr , dept , trypsin , enzyme , biochemistry , organic chemistry , biology , genetics
15 N NMR assignments were made to the backbone amide nitrogen atoms at natural isotopic abundance of intact and reactive‐site (Arg 5 —Ile 6 ) hydrolyzed Cucurbita maxima trypsin inhibitor III (CMTI‐III and CMTI‐III*, respectively) by means of 2D proton‐detected heteronuclear single bond chemical shift correlation (HSBC) spectroscopy, utilizing the previously made sequence‐specific 1 H NMR assignments (Krishnamoorthi et al. (1992) Biochemistry 31. 898–904). Comparison of the 15 N chemical shifts of the two forms of the inhibitor molecule revealed significant changes not only for residues located near the reactive‐site region, but also for those distantly located. Residues Cys 3 , Arg 5 , Leu 7 , Met 8 , Cys 10 , Cys 16 , Glu 19 , His 25 , Tyr 27 , Cys 28 and Gly 28 showed significant chemical shift changes ranging from 0.3 to 6.1 ppm, thus indicating structural perturbations that were transmitted throughout the molecule. These findings confirm the earlier conclusions based on 1 H NMR investigations.