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Imparting mineral affinity to proteins with thiol–labile disulfide linkages
Author(s) -
Bansal Geeti,
Wright Jennifer E. I.,
Zhang Sufeng,
Zernicke Ronald F.,
Uludag Hasan
Publication year - 2005
Publication title -
journal of biomedical materials research part a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.849
H-Index - 150
eISSN - 1552-4965
pISSN - 1549-3296
DOI - 10.1002/jbm.a.30334
Subject(s) - cysteine , conjugate , thiol , bovine serum albumin , cleavage (geology) , conjugated system , propionate , chemistry , in vitro , biochemistry , amino acid , disulfide bond , combinatorial chemistry , organic chemistry , materials science , polymer , enzyme , mathematical analysis , mathematics , fracture (geology) , composite material
Chemical conjugation of bisphosphonates (BPs) to proteins is an effective means to enhance binding of proteins to mineral‐containing biomaterials. BPs linked to proteins with reversible (i.e., cleavable) linkages were considered desirable over the conjugates linked with stable linkages because cleavable linkages allow protein release in free form from the mineral‐containing biomaterials. To explore the feasibility of creating cleavable BP‐protein conjugates, an amine‐ and a thiol‐containing BP were conjugated to the model protein Bovine Serum Albumin (BSA) with N ‐succinimidyl‐3‐(2‐pyridyldithio)propionate (SPDP), which resulted in disulfide‐linked BP–BSA conjugates. Although disulfide‐linked conjugates were stable under aqueous conditions, the conjugates in solution were readily cleaved in the presence of physiological concentrations (∼ 0.3 m M ) of the thiol compound, cysteine. The imparted mineral affinity as a result of BP conjugation, as assessed by hydroxyapatite (HA) binding in vitro , was lost upon cleavage of the disulfide‐linked BP. The conjugates bound to HA were also cleavable with cysteine, but their cleavage rate was significantly reduced as compared to the conjugates in solution. In conclusion, disulfide‐linked BP conjugates were shown to be readily cleavable by the amino acid cysteine and this resulted in the loss of imparted mineral affinity of the proteins. The proposed approach will be useful for modulating in vivo delivery of proteins implanted with mineral‐containing biomaterials. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005