Our studies include the relationships of biological function to the three-dimensional geometrical and electronic structures of enzymes and their complexes, and of smaller molecules. A recent major accomplishment, the structure to 2.5A resolution of the complex of the allosteric enzyme aspartate transcarbamylase with the potent inhibitor N-phosphonacetyl-L-aspartate, has revealed the active site, and the large conformational changes associated with the transition from the less active (T) form to the more active (R) form. With the use of the now-known diffraction phases, it is planned to relate the effects on three dimensional structure of (a) site specific mutagenesis, (b) chemical modification, (c) natural mutations, and (d) reconstituted hybrids of various catalytic and regulatory protein components. These structural data will be compared with the effects on activity and regulation in order to establish an atomic basis for allosteric behavior. X-ray diffraction studies are being carried out on new complexes of inhibitors and (at low temperatures) substrates with carboxypeptidase A, and on leucine aminopeptidase and a cytochrome P450 (a 17 hydroxylase). Theoretical molecular orbital studies of enzyme mechanisms and X-ray diffraction studies of structures of smaller biologically active molecules are also being made. These studies will illuminate aspects of mechanisms and help to account for the efficient catalytic powers of enzymes.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
4R37GM006920-32
Application #
3484062
Study Section
Special Emphasis Panel (NSS)
Project Start
1975-09-01
Project End
1996-03-31
Budget Start
1991-04-01
Budget End
1992-03-31
Support Year
32
Fiscal Year
1991
Total Cost
Indirect Cost
Name
Harvard University
Department
Type
Schools of Arts and Sciences
DUNS #
071723621
City
Cambridge
State
MA
Country
United States
Zip Code
02138
Lipscomb, William N; Kantrowitz, Evan R (2012) Structure and mechanisms of Escherichia coli aspartate transcarbamoylase. Acc Chem Res 45:444-53
Lipscomb, W N (1994) Aspartate transcarbamylase from Escherichia coli: activity and regulation. Adv Enzymol Relat Areas Mol Biol 68:67-151
Xue, Y; Huang, S; Liang, J Y et al. (1994) Crystal structure of fructose-1,6-bisphosphatase complexed with fructose 2,6-bisphosphate, AMP, and Zn2+ at 2.0-A resolution: aspects of synergism between inhibitors. Proc Natl Acad Sci U S A 91:12482-6
Chook, Y M; Gray, J V; Ke, H et al. (1994) The monofunctional chorismate mutase from Bacillus subtilis. Structure determination of chorismate mutase and its complexes with a transition state analog and prephenate, and implications for the mechanism of the enzymatic reaction. J Mol Biol 240:476-500
Zhang, Y; Liang, J Y; Huang, S et al. (1994) Toward a mechanism for the allosteric transition of pig kidney fructose-1,6-bisphosphatase. J Mol Biol 244:609-24
Reinisch, K M; Chen, L; Verdine, G L et al. (1994) Crystallization and preliminary crystallographic analysis of a DNA (cytosine-5)-methyltransferase from Haemophilus aegyptius bound covalently to DNA. J Mol Biol 238:626-9
Kim, H; Lipscomb, W N (1994) Structure and mechanism of bovine lens leucine aminopeptidase. Adv Enzymol Relat Areas Mol Biol 68:153-213
Xue, Y; Lipscomb, W N (1994) The crystallization and preliminary X-ray analysis of allosteric chorismate mutase. J Mol Biol 241:273-4
Gidh-Jain, M; Zhang, Y; van Poelje, P D et al. (1994) The allosteric site of human liver fructose-1,6-bisphosphatase. Analysis of six AMP site mutants based on the crystal structure. J Biol Chem 269:27732-8
Xue, Y; Lipscomb, W N; Graf, R et al. (1994) The crystal structure of allosteric chorismate mutase at 2.2-A resolution. Proc Natl Acad Sci U S A 91:10814-8

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