3IAQ

E. coli (lacz) beta-galactosidase (E416V)

Summary for 3IAQ

• Entry DOI: 10.2210/pdb3iaq/pdb
• Related: 1DP0 3DYM 3DYP 3IAP
• Descriptor: Beta-galactosidase, MAGNESIUM ION, SODIUM ION, ... (6 entities in total)
• Functional Keywords: glu-416-val beta-galactosidase hydrolase tim barrel(alpha/beta barrel) jelly-roll barrel immunoglobulin beta supersandwhich, glycosidase, hydrolase
• Biological source: Escherichia coli K-12
• Total number of polymer chains: 4
• Total formula weight: 474490.01

Authors

Lo, S.,Dugdale, M.L.,Jeerh, N.,Ku, T.,Roth, N.J.,Huber, R.E. (deposition date: 2009-07-14, release date: 2009-12-29, Last modification date: 2023-09-06)

Primary citation

Lo, S.,Dugdale, M.L.,Jeerh, N.,Ku, T.,Roth, N.J.,Huber, R.E.
Studies of Glu-416 variants of beta-galactosidase (E. coli) show that the active site Mg(2+) is not important for structure and indicate that the main role of Mg (2+) is to mediate optimization of active site chemistry
Protein J., 29:26-31, 2010

PubMed Abstract: Variants of beta-galactosidase with Valine and with Glutamine replacing Glutamate-416 did not have a Mg(2+) bound at the active site even at high Mg(2+) concentrations (200 mM). They had low catalytic activity and the pH profiles were very different from those of the native enzyme. In addition, substrates, substrate analogs, transition state analogs and galactose bound very poorly. However, the orientation and conformation of the Mg(2+) ligands (residues 416, 418, and 461) as well as the B-factors of these three side chains did not change significantly. The structures, conformations and B-factors of other active site residues were also essentially unchanged. These studies show that the active site Mg(2+) is not necessary for structure and is, therefore, mainly important for modulating the chemistry and mediating the interactions between the active site components.

PubMed: 19936901
DOI: 10.1007/s10930-009-9216-x

Experimental method

X-RAY DIFFRACTION (2.7 Å)