The isoelectric point of MTGase was approximately 8.9. The molecular weight of MTGase was previously determined to be ∼40,000 on both SDS-polyacrylamide electrophoresis (SDS-PAGE) and gel-permeation chromatography. More precise analysis, performed recently, has confirmed that MTGase has a molecular weight of 38,000. Protein sequencing by the automated Edman method and mass spectrometry also revealed the primary structure of MTGase, demonstrating that MTGase comprises of 331 amino acid residues (Fig. 2)[24]. The results from cDNA sequencing of the gene from the producing microorganism coincided well with the result of protein sequencing. It further suggested that MTGase possibly has a signal peptide of 18 amino acid residues at its amino terminal[21]. The overall sequence data indicate that MTGase has a single cysteine residue. The molecular weight calculated from the amino acid composition (331 residues) is 37,842, which is similar to the experimentally obtained value of 38,000. MTGase is, therefore, considered to be a monomeric and simple protein (not a glycoprotein or lipoprotein), although there are two potential glycosylation sites (-Thr-Xxx-Asn-) in the primary structure.