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Title: Structural mechanisms of nonplanar hemes in proteins

The objective is to assess the occurrence of nonplanar distortions of hemes and other tetrapyrroles in proteins and to determine the biological function of these distortions. Recently, these distortions were found by us to be conserved among proteins belonging to a functional class. Conservation of the conformation of the heme indicates a possible functional role. Researchers have suggested possible mechanisms by which heme distortions might influence biological properties; however, no heme distortion has yet been shown conclusively to participate in a structural mechanism of hemoprotein function. The specific aims of the proposed work are: (1) to characterize and quantify the distortions of the hemes in all of the more than 300 hemoprotein X-ray crystal structures in terms of displacements along the lowest-frequency normal coordinates, (2) to determine the structural features of the protein component that generate and control these nonplanar distortions by using spectroscopic studies and molecular-mechanics calculations for the native proteins, their mutants and heme-peptide fragments, and model porphyrins, (3) to determine spectroscopic markers for the various types of distortion, and, finally, (4) to discover the functional significance of the nonplanar distortions by correlating function with porphyrin conformation for proteins and model porphyrins.
Authors:
Publication Date:
OSTI Identifier:
477744
Report Number(s):
SAND--97-0915
ON: DE97006214; TRN: 97:003491
DOE Contract Number:
AC04-94AL85000
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: May 1997
Research Org:
Sandia National Labs., Albuquerque, NM (United States)
Sponsoring Org:
USDOE Office of Financial Management and Controller, Washington, DC (United States)
Country of Publication:
United States
Language:
English
Subject:
55 BIOLOGY AND MEDICINE, BASIC STUDIES; HEME; STRUCTURE-ACTIVITY RELATIONSHIPS; MUTANTS; PORPHYRINS; PROTEINS; PROTEIN STRUCTURE