2AIR

T-state Active Site of Aspartate Transcarbamylase:Crystal Structure of the Carbamyl Phosphate and L-alanosine Ligated Enzyme

Summary for 2AIR

• Entry DOI: 10.2210/pdb2air/pdb
• Descriptor: Aspartate carbamoyltransferase catalytic chain, Aspartate carbamoyltransferase regulatory chain, PHOSPHORIC ACID MONO(FORMAMIDE)ESTER, ... (6 entities in total)
• Functional Keywords: aspartate transcarbamylase, alanosine, carbamyl phosphate, t-state, transferase
• Biological source: Escherichia coli; More
• Total number of polymer chains: 4
• Total formula weight: 103672.53

Authors

Huang, J.,Lipscomb, W.N. (deposition date: 2005-07-30, release date: 2006-01-24, Last modification date: 2023-08-23)

Primary citation

Huang, J.,Lipscomb, W.N.
T-State Active Site of Aspartate Transcarbamylase: Crystal Structure of the Carbamyl Phosphate and l-Alanosine Ligated Enzyme
Biochemistry, 45:346-352, 2006

PubMed Abstract: An X-ray diffraction study to 2.0 A resolution shows that this enzyme, ATCase, is in the T-state (the c3 to c3 distance is 45.2 A) when ATCase is bound to carbamyl phosphate (CP) and to L-alanosine (an analogue of aspartate). This result strongly supports the kinetic results that alanosine did not inhibit the carbamylation of aspartate in the normal reaction of native ATCase plus CP and aspartate [Baillon, J., Tauc, P., and Hervé, G. (1985) Biochemistry 24, 7182-7187]. The structure further reveals that the phosphate of CP is 4 A away from its known position in the R-state and is in the T-state position of P(i) in a recent study of ATCase complexed with products, phosphate (P(i)) and N-carbamyl-L-aspartate [Huang, J., and Lipscomb, W. N. (2004) Biochemistry 43, 6422-6426]. Moreover, the alanosine position in this T-state is somewhat displaced from that expected for its analogue, aspartate, from the R-state position. The relations of these structural aspects to the kinetics are presented.

PubMed: 16401065
DOI: 10.1021/bi051543u

Experimental method

X-RAY DIFFRACTION (2 Å)