Glycoside Hydrolase Family 6

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• Author: ^^^Kathleen Piens^^^ and ^^^Gideon Davies^^^
• Responsible Curator: ^^^Gideon Davies^^^

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Glycoside Hydrolase Family GH6
Clan	none
Mechanism	inverting
Active site residues	acid known, base debated
CAZy DB link
http://www.cazy.org/fam/GH6.html

Substrate specificities

Endoglucanases (EC 3.2.1.4) and cellobiohydrolases (EC 3.2.1.91)only. Both classes of enzyme active on cellulose / beta 1,4 glucans.

Kinetics and Mechanism

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Catalytic Residues

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Table. Putative catalytic residues of some representatives in GH family 6 (with biochemical characterization of wt and mutant enzymes).

Proposed role	CfCel6A (endo)	HiCel6A (exo)	HjCel6A (exo)	TfCel6A (endo)	TfCel6B (exo)
Substrate distortion	Asp210	Tyr174	Tyr169	Tyr73	Tyr220
Increase in pKa acid/Catalytic base	Asp216	Asp180	Asp175	Asp79	Asp226
Proton network	Gly222	Ser186	Ser181	Ser85	Asp232
Catalytic acid	Asp252	Asp226	Asp221	Asp117	Asp274
Catalytic base/substrate binding	Asp392	Asp405	Asp401	Asp265	Asp497

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Three-dimensional structures

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Family Firsts

First sterochemistry determination

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

First general acid/base residue identification

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

First 3-D structure

The catalytic core domain of the Trichoderma reesei (the organism now known as Hypocrea jecorina) cellobiohydrolase II by the Jones group [3]. The first endoglucanase in this family was the Thermomonospora fusca E2 enzyme (catalytic core) solved by the Wilson/Karplus groups[4]

References

3. Rouvinen J, Bergfors T, Teeri T, Knowles JK, and Jones TA. (1990). Three-dimensional structure of cellobiohydrolase II from Trichoderma reesei. Science. 1990;249(4967):380-6. DOI:10.1126/science.2377893 |
4. Spezio M, Wilson DB, and Karplus PA. (1993). Crystal structure of the catalytic domain of a thermophilic endocellulase. Biochemistry. 1993;32(38):9906-16. DOI:10.1021/bi00089a006 |
5. Robert V. Stick and Spencer J. Williams. (2009) Carbohydrates. Elsevier Science.

6. Sinnott, M.L. (1990) Catalytic mechanisms of enzymic glycosyl transfer. Chem. Rev. 90, 1171-1202. DOI: 10.1021/cr00105a006