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Glycoside Hydrolase Family 53

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Glycoside Hydrolase Family GH53
Clan GH-A
Mechanism retaining
Active site residues known
CAZy DB link
http://www.cazy.org/fam/GH53.html


Substrate specificities

The only known specificity for this family is beta-1,4-galactanase (EC 3.2.1.89) and the only reported function is the microbial degradation of galactans and arabinogalactans in the pectic component of plant cell walls. A number of patents on industrial applications of GH53 have been filed.

Kinetics and Mechanism

GH53 beta-1,4-galactanases follow a classical retaining mechanism (Ref.). Most characterized members have been reported to have an endo-mode of action (refs), although processivity has been suggested in one case (Ref).

Catalytic Residues

Two glutamates act as catalytic residues, as nucleophile and acid-base catalyst respectively, and were first identified by Braithwhite et al,.

Three-dimensional structures

Content is to be added here.


Family Firsts

First sterochemistry determination
Cite some reference here, with a short (1-2 sentence) explanation [1].
First catalytic nucleophile identification
Cite some reference here, with a short (1-2 sentence) explanation [2].
First general acid/base residue identification
Cite some reference here, with a short (1-2 sentence) explanation [3].
First 3-D structure
Cite some reference here, with a short (1-2 sentence) explanation [4].

References

  1. Comfort DA, Bobrov KS, Ivanen DR, Shabalin KA, Harris JM, Kulminskaya AA, Brumer H, and Kelly RM. (2007). Biochemical analysis of Thermotoga maritima GH36 alpha-galactosidase (TmGalA) confirms the mechanistic commonality of clan GH-D glycoside hydrolases. Biochemistry. 2007;46(11):3319-30. DOI:10.1021/bi061521n | PubMed ID:17323919 [Comfort2007]
  2. Sinnott, M.L. (1990) Catalytic mechanisms of enzymic glycosyl transfer. Chem. Rev. 90, 1171-1202. DOI: 10.1021/cr00105a006

    [MikesClassic]
  3. He S and Withers SG. (1997). Assignment of sweet almond beta-glucosidase as a family 1 glycosidase and identification of its active site nucleophile. J Biol Chem. 1997;272(40):24864-7. DOI:10.1074/jbc.272.40.24864 | PubMed ID:9312086 [He1999]
  4. Robert V. Stick and Spencer J. Williams. (2009) Carbohydrates. Elsevier Science. [3]

All Medline abstracts: PubMed