Glycoside Hydrolase Family 102

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• Author: ^^^Anthony Clarke^^^
• Responsible Curator: ^^^Anthony Clarke^^^

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Glycoside Hydrolase Family GHnn
Clan	GH-x
Mechanism	retaining/inverting
Active site residues	known/not known
CAZy DB link
http://www.cazy.org/fam/GHnn.html

Substrate specificities

The glycoside hydrolases of this family are lytic transglyosylases (also referred to as peptidoglycan lyases) of bacterial origin and they constitute family 2 of the classification scheme of Blackburn and Clarke [1]. The prototype for this family is membrane-bound lytic transglycosylase A (MltA) from Escherichia coli. These enzymes cleave the β-1,4 linkage between N-acetylmuramoyl and N-acetylglucosaminyl residues in peptidoglycan (Figure 1), but unlike the lytic transglycosylases of other families, they are active on peptidoglycan fragments lacking their stem peptides [2]. No other activities have been observed.

Kinetics and Mechanism

Figure 1. Lytic and hydrolytic pathways of GH23 enzymes. GEWL, g-type lysozymes; LT, lytic transglycosylase. (click to enlarge).

The lytic transglycosidases, strictly speaking, are retaining enzymes. However, they are not hydrolases but rather catalyse an intramolecular glycosyl transferase reaction onto the C-6 hydroxyl group of the muramoyl residue leading to the generation of a terminal 1,6-anhdyromuramoyl product thus lacking a reducing end [3]. No detailed analyses involving both steady state and pre-steady state kinetic studies have been reported.

Catalytic Residues

Content is to be added here.

Three-dimensional structures

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Family Firsts

First sterochemistry determination

Cite some reference here, with a short (1-2 sentence) explanation [4].

First catalytic nucleophile identification

Cite some reference here, with a short (1-2 sentence) explanation [5].

First general acid/base residue identification

Cite some reference here, with a short (1-2 sentence) explanation [6].

First 3-D structure

Cite some reference here, with a short (1-2 sentence) explanation [3].

References

2. Ursinus A and Höltje JV. (1994). Purification and properties of a membrane-bound lytic transglycosylase from Escherichia coli. J Bacteriol. 1994;176(2):338-43. DOI:10.1128/jb.176.2.338-343.1994 |

[[Category:Glycoside Hydrolase Families|GH102]