Study on the mechanism of molecular recognition between the glycosyl transferase and the core-peptide controlling heparin biosynthesis

糖胺多聚糖(Gacs)分为肝素型和软骨素型两类，性质不同。然而，第一个氨基己糖残基将GAG分类为这两类的糖基转移机制尚不清楚。这一事实促使我们合成了可直接用于酶促多糖延伸的蛋白多糖探针，以阐明分选机制。据我们所知，肝素型的GAG通常与核心肽的疏水性和邻近的酸性区域相连。这表明，第一个氨基己糖基转移酶识别与特定多肽协调的环境，以确定GAG的类别。因此，我们选择了由连接到疏水和酸性多肽上的Glca-Gal-Gal-Xyl组成的四糖低聚肽，即β-葡聚糖的部分序列，作为合成的目标化合物。在项目初期，用液相法合成了相应的四糖六肽。用固体载体合成法也得到了相同类型的化合物，其合成方案导致了相应的四糖十六肽的成功形成。在本项目期间，合成了目标糖基低聚肽，并建立了固体载体法合成蛋白多糖的方法。

Glycosaminoglycans (GACs) are classified into two categories having different properties; heparin-type and chondroitin-type. However, glycosyl transfer mechanisms of the first hexosamine residue sorting the GAG into these two categories, are unknown. This fact prompted us to synthesize the proteoglycan probe that could be directly used for the enzymatic glycan elongation in order to elucidate the sorting mechanisms. So far as we know, it has been appointed that the heparin-type of GAG often linked to the hydrophobic and the neighboring acidic regions of the core-peptide. This suggests that the first hexosaminyl transferase recognizes the environment coordinated with the specific peptides to determine the category of GAG. Thus, the tetraosyl oligopeptides composed of GlcA-Gal-Gal-Xyl linking to the hydrophobic and acidic peptides, a partial sequence of the betaglycan, have been selected as the targeted compound to be synthesized. At the beginning of the project, the corresponding tetraosyl hexapeptide was synthesized with liquid phase method. The same type compound was also obtained with the solid support synthesis, of which synthetic protocol led to the successful formation of the corresponding tetraosyl hexadecapeptide. Within the term of this project, the targeted glycosyl oligopeptides were synthesized and proteoglycan synthesis with solid support method was also established.