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Human spermatid‐specific thioredoxin‐1 (Sptrx‐1) is a two‐domain protein with oxidizing activity
Author(s) -
Jiménez Alberto,
Johansson Catrine,
Ljung Johanna,
Sagemark Johan,
Berndt Kurt D,
Ren Bin,
Tibbelin Gudrun,
Ladenstein Rudolf,
Kieselbach Thomas,
Holmgren Arne,
Gustafsson Jan-Åke,
Miranda-Vizuete Antonio
Publication year - 2002
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(02)03417-8
Subject(s) - thioredoxin , spermatid , circular dichroism , biochemistry , chemistry , enzyme , size exclusion chromatography , cysteine , protein structure , biophysics , biology , sperm , botany
Spermatid‐specific thioredoxin‐1 (Sptrx‐1) is the first member of the thioredoxin family of proteins with a tissue‐specific expression pattern, found exclusively in the tail of elongating spermatids and spermatozoa. We describe here further biochemical characterization of human Sptrx‐1 protein structure and enzymatic activity. In gel filtration chromatography human Sptrx‐1 eluates as a 400 kDa protein consistent with either an oligomeric form, not maintained by intermolecular disulfide bonding, and/or a highly asymmetrical structure. Analysis of circular dichroism spectra of fragments 1–360 and 361–469 and comparison to spectra of full‐length Sptrx‐1 supports a two‐domain organization with a largely unstructured N‐terminal domain and a folded thioredoxin‐like C‐terminal domain. Functionally, Sptrx‐1 behaves as an oxidant in vitro when using selenite, but not oxidized glutathione, as electron acceptor. This oxidizing enzymatic activity suggests that Sptrx‐1 might govern the stabilization (by disulfide cross‐linking) of the different structures in the developing tail of spermatids and spermatozoa.