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Parathyroid hormone is a heparin/polyanion binding protein: Binding energetics and structure modification
Author(s) -
Kamerzell Tim J.,
Joshi Sangeeta B.,
McClean Donald,
Peplinskie Lori,
Toney Karen,
Papac Damon,
Li Meili,
Middaugh C. Russell
Publication year - 2007
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.062613807
Subject(s) - chemistry , parathyroid hormone , heparin , biochemistry , circular dichroism , energetics , protein structure , biophysics , crystallography , calcium , organic chemistry , biology , ecology
The interaction of four representative polyanions with parathyroid hormone (PTH) residues 1–84 has been investigated utilizing a variety of spectroscopic and calorimetric techniques. Each of the polyanions employed demonstrate enthalpically driven binding to PTH (1–84) with significant affinity. The polyanions heparin, dextran sulfate, phytic acid, and sucrose octasulfate induce α‐helical structure in PTH to varying extents depending on the ratio of polyanion to protein employed. Intrinsic and extrinsic fluorescence spectroscopy suggests significant protein tertiary structure alteration upon polyanion binding. Although structural modification occurred upon polyanion binding, PTH colloidal stability was increased depending on the ratio of polyanion to protein used. Nevertheless, the bioactivity of PTH in the presence of various ratios of heparin was not altered. The potential biological significance of PTH/polyanion interactions is discussed.