IUBMB Enzyme Nomenclature


Accepted name: S-methyl-5-thioribulose 1-phosphate isomerase

Reaction: (1) S-methyl-5-thio-D-ribulose 1-phosphate = S-methyl-1-thio-D-xylulose 5-phosphate
(2) S-methyl-5-thio-D-ribulose 1-phosphate = S-methyl-1-thio-D-ribulose 5-phosphate

Other name(s): rlp (gene name); 5-methylthioribulose-1-phosphate isomerase (incorrect)

Systematic name: S-methyl-5-thio-D-ribulose 1-phosphate 1,3-isomerase

Comments: The enzyme, characterized from the bacterium Rhodospirillum rubrum, participates in methionine salvage from S-methyl-5'-thioadenosine. It is a RubisCO-like protein (RLP) that is not capable of carbon fixation, and catalyses an isomerization reaction that converts S-methyl-5-thio-D-ribulose 1-phosphate to a 3:1 mixture of S-methyl-1-thioxylulose 5-phosphate and S-methyl-1-thioribulose 5-phosphate. The reaction is an overall 1,3-proton transfer, which likely consists of two 1,2-proton transfer events.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:


1. Imker, H.J., Singh, J., Warlick, B.P., Tabita, F.R. and Gerlt, J.A. Mechanistic diversity in the RuBisCO superfamily: a novel isomerization reaction catalyzed by the RuBisCO-like protein from Rhodospirillum rubrum. Biochemistry 47 (2008) 11171-11173. [PMID: 18826254]

2. Erb, T.J., Evans, B.S., Cho, K., Warlick, B.P., Sriram, J., Wood, B.M., Imker, H.J., Sweedler, J.V., Tabita, F.R. and Gerlt, J.A. A RubisCO-like protein links SAM metabolism with isoprenoid biosynthesis. Nat. Chem. Biol. 8 (2012) 926-932. [PMID: 23042035]

[EC created 2021]

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