5x52
Human serum albumin complexed with octanoate and N-acetyl-L-methionine
Structural highlights
DiseaseALBU_HUMAN Defects in ALB are a cause of familial dysalbuminemic hyperthyroxinemia (FDH) [MIM:103600. FDH is a form of euthyroid hyperthyroxinemia that is due to increased affinity of ALB for T(4). It is the most common cause of inherited euthyroid hyperthyroxinemia in Caucasian population.[1] [2] [3] [4] FunctionALBU_HUMAN Serum albumin, the main protein of plasma, has a good binding capacity for water, Ca(2+), Na(+), K(+), fatty acids, hormones, bilirubin and drugs. Its main function is the regulation of the colloidal osmotic pressure of blood. Major zinc transporter in plasma, typically binds about 80% of all plasma zinc.[5] Publication Abstract from PubMedDuring pasteurization and storage of albumin products, Sodium octanoate (Oct) and N-acethyl-L-tryptophan (N-AcTrp) are used as the thermal stabilizer and the antioxidant for human serum albumin (HSA), respectively. We recently reported that N-acethyl-L-methionine (N-AcMet) is an antioxidant for HSA, which is superior to N-AcTrp when it is especially exposed to light during storage. The objective of the present study is to clarify the molecular mechanism responsible for the HSA protective effect of Oct and N-AcMet based on their ternary complex structure. Crystal structure of the HSA-Oct-N-AcMet complex showed that one N-AcMet molecule is bound to the entrance of drug site 1 of HSA, and its side chain, which is susceptible to the oxidation, is exposed to the solvent. At the same time, two Oct binding sites are observed in drug sites 1 and 2 of HSA, respectively, and each Oct molecule occupies the hydrophobic cavity in them. These results indicate the molecular mechanism responsible for the HSA stabilization by these small molecules as follows. N-AcMet seals the entrance of drug site 1 while it acts as an antioxidant for HSA. Oct is chiefly bound to drug site 2 of HSA and it increases the thermal stability of HSA because of the occupying the largest intra-cavity of sub-domain IIIA in HSA. These findings suggest that N-AcMet acts positively as useful stabilizer for albumin formulated products such as functionalized HSA and HSA fusion proteins. Crystallographic analysis of the Ternary Complex of Octanoate and N-acetyl-L-methionine with Human Serum Albumin Reveals the Mode of their Stabilizing Interactions.,Kawai A, Chuang VTG, Kouno Y, Yamasaki K, Miyamoto S, Anraku M, Otagiri M Biochim Biophys Acta. 2017 May 1. pii: S1570-9639(17)30080-8. doi:, 10.1016/j.bbapap.2017.04.004. PMID:28473296[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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