Trimble R B, Tarentino A L, Evans G, Maley F
J Biol Chem. 1979 Oct 10;254(19):9708-13.
An enzyme, previously described as endo-beta-N-acetylglucosaminidase L (Tarentino, A.L., and Maley, F. (1974) J. Biol. Chem. 249, 811-817) because of its apparent specificity for Man(GlcNAc)2Asn, has been purified to homogeneity. The enzyme has now been found to hydrolyze (GlcNAc)3 to (GlcNAc)2 plus GlcNAc, and (GlcNAc)4 to 2(GlcNAc)2, at twice the rate observed for Man(GlcNAc)2Asn. Removal of the asparagine from the latter compound reduces the rate of hydrolysis by about 30-fold. Reduction of (GlcNAc)3 to GlcNAc beta 1 leads to 4GlcNAc beta 1 leads to 4GlcNAc-ol eliminates this compound as a substrate for endo-beta-N-acetylglucosaminidase L. However, the reduction of (GlcNAc)4 does not affect its rate of hydrolysis. Endo-beta-N-acetylglucosaminidase L consists of a single polypeptide chain with a molecular weight of 49,500 +/- 400, which on isoelectric focusing separates into two closely migrating bands; a major with a pI of 4.25 and a minor one with a pI 4.20. Both bands possess similar enzyme activities and amino acid compositions, but differ slightly in their tryptic peptide maps.
一种酶，先前因其对Man(GlcNAc)2Asn具有明显特异性而被描述为内切-β-N-乙酰氨基葡萄糖苷酶L（塔伦蒂诺，A.L.，和马利，F.（1974年）《生物化学杂志》249卷，811 - 817页），现已被纯化至同质。现已发现该酶能将(GlcNAc)3水解为(GlcNAc)2加GlcNAc，将(GlcNAc)4水解为2(GlcNAc)2，水解速率是Man(GlcNAc)2Asn的两倍。从后一种化合物中去除天冬酰胺会使水解速率降低约30倍。将(GlcNAc)3还原为GlcNAcβ1→4GlcNAcβ1→4GlcNAc - ol会使该化合物不再作为内切-β-N-乙酰氨基葡萄糖苷酶L的底物。然而，(GlcNAc)4的还原并不影响其水解速率。内切-β-N-乙酰氨基葡萄糖苷酶L由一条分子量为49,500±400的单一多肽链组成，在等电聚焦时可分离成两条迁移紧密的条带；一条主要条带的pI为4.25，一条次要条带的pI为4.20。两条带都具有相似的酶活性和氨基酸组成，但胰蛋白酶肽图谱略有不同。
