MUCIN SYNTHESIS .7. CONVERSION OF R1-BETA-1-3GAL-R2 TO R1-BETA-1-3(GLCNAC-BETA-1-6)GAL-R2 AND OF R1-BETA-1-3GALNAC-R2 TO R1-BETA-1-3(GLCNAC-BETA-1-6)GALNAC-R2 BY A BETA-6-N-ACETYLGLUCOSAMINYLTRANSFERASE IN PIG GASTRIC-MUCOSA
MUCIN SYNTHESIS .7. CONVERSION OF R1-BETA-1-3GAL-R2 TO R1-BETA-1-3(GLCNAC-BETA-1-6)GAL-R2 AND OF R1-BETA-1-3GALNAC-R2 TO R1-BETA-1-3(GLCNAC-BETA-1-6)GALNAC-R2 BY A BETA-6-N-ACETYLGLUCOSAMINYLTRANSFERASE IN PIG GASTRIC-MUCOSA
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DOI：
10.1111/j.1432-1033.1986.tb09690.x
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发表时间：
1986-06-16
期刊：
影响因子：
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通讯作者：
VANDENEIJNDEN, DH
中科院分区：
文献类型：
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作者：
BROCKHAUSEN, I;MATTA, KL;VANDENEIJNDEN, DH
来自猪胃粘膜微粒体的UDP-GlcNAc：R1-β 1 -3Gal（NAc）-R2 [GlcNAc至Gal（NAc）] β 6-N-乙酰葡糖胺基转移酶活性催化从GlcNAc β 1 -3Gal-R形成GlcNAc β 1 -3（GlcNAc β 1 -6）Gal-R，其中-R是-β 1 -3GalNAc-α-苄基或-β 1 -3（GlcNAc β 1 -6）GalNAc-α-苄基。因此，这种酶参与粘蛋白型寡糖中I抗原决定簇的合成。该酶还将Gal β 1 - 3Gal β 1 -4Glc转化为Gal β 1 -3（GlcNAc β 1 -6）Gal β 1 -4Glc。该酶在0和0.2%之间的浓度被Triton X-100刺激，并且在0.5%被Triton X-100抑制。不需要Mn 2+，在10 mM EDTA存在下酶活性降低至65%。纯化酶产物并通过质子NMR、甲基化分析和β-甲基化分析鉴定。半乳糖苷酶消化。竞争研究表明，这种猪胃粘膜β 6-GlcNAc-转移酶活性是由于将Gal β 1 -3GalNAc-R转化为粘蛋白核心2、Gal β 1 -3（GlcNAc β 1 -6）GalNAc-R和将GlcNAc β 1 -3GalNAc-R转化为粘蛋白核心4、GlcNAc β 1 -3（GlcNAc β 1 -6）GalNAc-R的相同酶。底物特异性研究表明，该酶将GlcNAc连接到β-半乳糖苷酶中的Gal或GalNAc上。(1-6)连接，条件是这些残基在β中被取代。(1-3)通过GlcNAc或Gal连接。将GlcNAc β 1 -3残基插入到Gal β 1 -3GalNAc-R中以形成GlcNAc β 1 - 3Gal β 1 -3GalNAc-R阻止了GlcNAc插入到GalNAc中。这些研究建立了粘蛋白型低聚糖生物合成的几种新途径。
A UDP-GlcNAc:R1-.beta.1-3Gal(NAc)-R2 [GlcNAc to Gal(NAc)] .beta.6-N-acetylglucosaminyltransferase activity from pig pastric mucose microsomes catalyzes the formation of GlcNAc.beta.1-3(GlcNAc.beta.1-6)Gal-R from GlcNAc.beta.1-3Gal-R where -R is -.beta.1-3GalNAc-.alpha.-benzyl or -.beta.1-3(GlcNAc.beta.1-6)GalNAc-.alpha.-benzyl. This enzyme is therefore involved in the synthesis of the I antigenic determinant in mucin-type oligosaccharides. The enzyme also converts Gal.beta.1-3Gal.beta.1-4Glc to Gal.beta.1-3(GlcNAc.beta.1-6)Gal.beta.1-4Glc. The enzyme was stimulated by Triton X-100 at concentrations between 0 and 0.2% and was inhibited by Triton X-100 at 0.5%. There is no requirement for Mn2+ and the enzyme activity is reduced to 65% in the presence of 10 mM EDTA. Enzyme products were purified and identified by proton NMR, methylation analysis and .beta.-galactosidase digestion. Competition studies suggest that this pig gastric mucosal .beta.6-GlcNAc-transferase activity is due to the same enzyme that converts Gal.beta.1-3GalNAc-R to mucin core 2, Gal.beta.1-3(GlcNAc.beta.1-6)GalNAc-R, and GlcNAc.beta.1-3GalNAc-R to mucin core 4, GlcNAc.beta.1-3(GlcNAc.beta.1-6)GalNAc-R. Substrate specificity studies indicate that the enzyme attaches GlcNAc to either Gal or GalNAc in .beta.(1-6) linkage, provided these residues are substituted in .beta.(1-3) linkage by either GlcNAc or Gal. The insertion of a GlcNAc.beta.1-3 residue into Gal.beta.1-3GalNAc-R to form GlcNAc.beta.1-3Gal.beta.1-3GalNAc-R prevents insertion of GlcNAc into GalNAc. These studies establish several novel pathways in mucin-type oligosaccharide biosynthesis.