title: A novel α-glucosidase inhibitor protein from the rhizomes of Zingiber ottensii valeton.
abstract: The objective of this study was to investigate a new protein with α-glucosidase inhibitory activity from the rhizomes of Zingiber ottensii. With a simple salting-out technique followed by single-step anion-exchange purification, the protein was successfully purified from the rhizomes. This protein was found to have three likely sub-unit types, 32.5, 15.2, and 13.8 kDa, as revealed by native and reducing SDS-PAGE analysis. Determination of the kinetics of the inhibition of α-glucosidase from Saccharomyces cerevisiae by standard enzymatic methods indicated the maximum percent inhibition; IC(50) and K ( i ) of this protein were 77.5%, 30.15 μg/ml, and 140 μmol, while the K ( m ) and V ( max ) were 2.35 μmol and 0.11 mM/min, respectively. The inhibitory action was pH-independent within the pH range 2-10, but was potentially affected by buffer salts, and was relatively temperature-stable between 4-35 °C, with a maximum activity at 65 °C. The amino acid sequence of an internal fragment of this purified Z. ottensii rhizomal protein had a similarity to the sequence from the plant cysteine proteinase family. Although this α-glucosidase inhibitory protein was purified from Z. ottensii rhizomes and preliminarily characterized, further studies are needed prior to firm applications being envisaged.
authors.affiliation: Chulalongkorn University, Bangkok, Thailand.
authors.forename: Nathachai
authors.initials: N
authors.lastname: Tiengburanatam
authors.forename: Apaporn
authors.initials: A
authors.lastname: Boonmee
authors.forename: Polkit
authors.initials: P
authors.lastname: Sangvanich
authors.forename: Aphichart
authors.initials: A
authors.lastname: Karnchanatat
mesh_terms: D000595:Amino Acid Sequence; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D065089:Glycoside Hydrolase Inhibitors; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000494:pharmacology*; D027343:Rhizome / Q000737:chemistry / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000201:enzymology; D029701:Saccharomyces cerevisiae Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry; D016415:Sequence Alignment; D019862:Zingiberales / Q000737:chemistry* / Q000235:genetics; D000520:alpha-Glucosidases / Q000737:chemistry
chemical_list: D004791:Enzyme Inhibitors; D065089:Glycoside Hydrolase Inhibitors; D010940:Plant Proteins; D029701:Saccharomyces cerevisiae Proteins; D000520:alpha-Glucosidases