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Carbamoyl phosphate synthetase: a tunnel runs through it
H M Holden1, J B Thoden, F M Raushel
1Department of Biochemistry University of Wisconsin Madison WI 53706 USA. holden@enzyme.wisc.edu
Current Opinion in Structural Biology
|January 23, 1999
Abstract:
The direct transfer of metabolites from one protein to another in a biochemical pathway or between one active site and another within a single enzyme has been described as substrate channeling. The first structural visualization of such a phenomenon was provided by the X-ray crystallographic analysis of tryptophan synthase, in which a tunnel of approximately 25 A in length was observed. The recently determined three-dimensional structure of carbamoyl phosphate synthetase sets a new long distance record in that the three active sites are separated by nearly 100 A.