Partially folded conformations of inositol monophosphatase endowed with catalytic activity

C. K. Lau; S. C. Lo; W. Li; D. R. Churchich; F. Kwok; J. E. Churchich

doi:10.1023/A:1020726318091

Partially folded conformations of inositol monophosphatase endowed with catalytic activity

C. K. Lau, S. C. Lo, W. Li, D. R. Churchich, F. Kwok, J. E. Churchich

Research output: Journal Publications and Reviews › RGC 21 - Publication in refereed journal › peer-review

2 Citations (Scopus)

Abstract

The stability of porcine brain inositol monophosphatase in the presence of increasing concentrations of urea was investigated at pH 7.5. Exposure of the enzyme to 8 M urea brings about the dissociation of the dimeric species of 58 kDa into monomeric forms as revealed by gel filtration chromatography. Unfolding of the protein by 8 M urea results in a decrease of the ellipticity at 220 nm (20%) together with a perturbation of the near-UV circular dichroism spectrum. Urea-treated inositol monophosphatase binds Co²⁺ ions with a dissociation constant of 3.3 μM. The enzyme is catalytically competent when assayed with 4-nitrophenyl-phosphate in the presence of the activating ion Co²⁺ at pH 7.5 in 8 M urea. The apparent activation constant for Co²⁺ is 2.5 mM. It is postulated that partially folded conformations of monomeric species preserve their catalytic function because the affinity of Co²⁺ ions for the metal coordination center of the protein is not perturbed by exposure to 8 M urea.

Original language	English
Pages (from-to)	789-797
Journal	Journal of Protein Chemistry
Volume	17
Issue number	8
DOIs	https://doi.org/10.1023/A:1020726318091
Publication status	Published - 1998
Externally published	Yes

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Publication details (e.g. title, author(s), publication statuses and dates) are captured on an “AS IS” and “AS AVAILABLE” basis at the time of record harvesting from the data source. Suggestions for further amendments or supplementary information can be sent to [email protected].

Research Keywords

Folding
Inositol monophosphatase
Molten globule
Monomeric species
Urea denaturation

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title = "Partially folded conformations of inositol monophosphatase endowed with catalytic activity",

abstract = "The stability of porcine brain inositol monophosphatase in the presence of increasing concentrations of urea was investigated at pH 7.5. Exposure of the enzyme to 8 M urea brings about the dissociation of the dimeric species of 58 kDa into monomeric forms as revealed by gel filtration chromatography. Unfolding of the protein by 8 M urea results in a decrease of the ellipticity at 220 nm (20%) together with a perturbation of the near-UV circular dichroism spectrum. Urea-treated inositol monophosphatase binds Co2+ ions with a dissociation constant of 3.3 μM. The enzyme is catalytically competent when assayed with 4-nitrophenyl-phosphate in the presence of the activating ion Co2+ at pH 7.5 in 8 M urea. The apparent activation constant for Co2+ is 2.5 mM. It is postulated that partially folded conformations of monomeric species preserve their catalytic function because the affinity of Co2+ ions for the metal coordination center of the protein is not perturbed by exposure to 8 M urea.",

keywords = "Folding, Inositol monophosphatase, Molten globule, Monomeric species, Urea denaturation",

author = "Lau, {C. K.} and Lo, {S. C.} and W. Li and Churchich, {D. R.} and F. Kwok and Churchich, {J. E.}",

note = "Publication details (e.g. title, author(s), publication statuses and dates) are captured on an “AS IS” and “AS AVAILABLE” basis at the time of record harvesting from the data source. Suggestions for further amendments or supplementary information can be sent to [email protected].",

year = "1998",

doi = "10.1023/A:1020726318091",

language = "English",

volume = "17",

pages = "789--797",

journal = "Journal of Protein Chemistry",

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TY - JOUR

T1 - Partially folded conformations of inositol monophosphatase endowed with catalytic activity

AU - Lau, C. K.

AU - Lo, S. C.

AU - Li, W.

AU - Churchich, D. R.

AU - Kwok, F.

AU - Churchich, J. E.

N1 - Publication details (e.g. title, author(s), publication statuses and dates) are captured on an “AS IS” and “AS AVAILABLE” basis at the time of record harvesting from the data source. Suggestions for further amendments or supplementary information can be sent to [email protected].

PY - 1998

Y1 - 1998

N2 - The stability of porcine brain inositol monophosphatase in the presence of increasing concentrations of urea was investigated at pH 7.5. Exposure of the enzyme to 8 M urea brings about the dissociation of the dimeric species of 58 kDa into monomeric forms as revealed by gel filtration chromatography. Unfolding of the protein by 8 M urea results in a decrease of the ellipticity at 220 nm (20%) together with a perturbation of the near-UV circular dichroism spectrum. Urea-treated inositol monophosphatase binds Co2+ ions with a dissociation constant of 3.3 μM. The enzyme is catalytically competent when assayed with 4-nitrophenyl-phosphate in the presence of the activating ion Co2+ at pH 7.5 in 8 M urea. The apparent activation constant for Co2+ is 2.5 mM. It is postulated that partially folded conformations of monomeric species preserve their catalytic function because the affinity of Co2+ ions for the metal coordination center of the protein is not perturbed by exposure to 8 M urea.

AB - The stability of porcine brain inositol monophosphatase in the presence of increasing concentrations of urea was investigated at pH 7.5. Exposure of the enzyme to 8 M urea brings about the dissociation of the dimeric species of 58 kDa into monomeric forms as revealed by gel filtration chromatography. Unfolding of the protein by 8 M urea results in a decrease of the ellipticity at 220 nm (20%) together with a perturbation of the near-UV circular dichroism spectrum. Urea-treated inositol monophosphatase binds Co2+ ions with a dissociation constant of 3.3 μM. The enzyme is catalytically competent when assayed with 4-nitrophenyl-phosphate in the presence of the activating ion Co2+ at pH 7.5 in 8 M urea. The apparent activation constant for Co2+ is 2.5 mM. It is postulated that partially folded conformations of monomeric species preserve their catalytic function because the affinity of Co2+ ions for the metal coordination center of the protein is not perturbed by exposure to 8 M urea.

KW - Folding

KW - Inositol monophosphatase

KW - Molten globule

KW - Monomeric species

KW - Urea denaturation

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U2 - 10.1023/A:1020726318091

DO - 10.1023/A:1020726318091

M3 - RGC 21 - Publication in refereed journal

C2 - 9988525

SN - 0277-8033

VL - 17

SP - 789

EP - 797

JO - Journal of Protein Chemistry

JF - Journal of Protein Chemistry

IS - 8

ER -

Partially folded conformations of inositol monophosphatase endowed with catalytic activity

Abstract

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Research Keywords

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