4rsd
From Proteopedia
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STRUCTURE OF THE D121A VARIANT OF RIBONUCLEASE A
Overview
The side chains of histidine and aspartate residues form a hydrogen bond, in the active sites of many enzymes. In serine proteases, the His...Asp, hydrogen bond of the catalytic triad is known to contribute greatly to, catalysis, perhaps via the formation of a low-barrier hydrogen bond. In, bovine pancreatic ribonuclease A (RNase A), the His...Asp dyad is composed, of His119 and Asp121. Previously, site-directed mutagenesis was used to, show that His119 has a fundamental role, to act as an acid during, catalysis of RNA cleavage [Thompson, J. E., and Raines, R. T. (1994) J., Am. Chem. Soc. 116, 5467-5468]. Here, Asp121 was replaced with an, asparagine or alanine residue. The crystalline structures of the two, variants were determined by X-ray diffraction analysis to a resolution of, 1.6 A ... [(full description)]
About this Structure
4RSD is a [Single protein] structure of sequence from [Bos taurus] with ACT and CL as [ligands]. Active as [Pancreatic ribonuclease], with EC number [3.1.27.5]. Structure known Active Sites: B1, B2, P1 and P2. Full crystallographic information is available from [OCA].
Reference
His...Asp catalytic dyad of ribonuclease A: structure and function of the wild-type, D121N, and D121A enzymes., Schultz LW, Quirk DJ, Raines RT, Biochemistry. 1998 Jun 23;37(25):8886-98. PMID:9636030
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