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Articles by K Lau
Total Records ( 2 ) for K Lau
  J Cheng , S Huang , H Yu , Y Li , K Lau and X. Chen
 

Trans-sialidases catalyze the transfer of a sialic acid from one sialoside to an acceptor to form a new sialoside. 2,3-Trans-sialidase activity was initially discovered in the parasitic protozoan Trypanosoma cruzi, and more recently was found in a multifunctional Pasteurella multocida sialyltransferase PmST1. 2,8-Trans-sialidase activity was also described for a multifunctional Campylobacter jejuni sialyltransferase CstII. We report here the discovery of the 2,6-trans-sialidase activity of a previously reported recombinant truncated bacterial 2,6-sialyltransferase from Photobacterium damsela (15Pd2,6ST). This is the first time that the 2,6-trans-sialidase activity has ever been identified. Kinetic studies indicate that 15Pd2,6ST-catalyzed trans-sialidase reaction follows a ping-pong bi-bi reaction mechanism. Cytidine 5'-monophosphate, the product of sialyltransferase reactions, is not required by the trans-sialidase activity of the enzyme but enhances the trans-sialidase activity modestly as a non-essential activator. Using chemically synthesized Neu5AcpNP and LacβMU, 2,6-linked sialoside Neu5Ac2,6LacβMU has been obtained in one-step in high yield using the trans-sialidase activity of 15Pd2,6ST. In addition to the 2,6-trans-sialidase activity, 15Pd2,6ST also has 2,6-sialidase activity. The multifunctionality is thus a common feature of many bacterial sialyltransferases.

  L Zhang , K Lau , J Cheng , H Yu , Y Li , G Sugiarto , S Huang , L Ding , V Thon , P. G Wang and X. Chen
 

Lewis x (Lex) and sialyl Lewis x (SLex)-containing glycans play important roles in numerous physiological and pathological processes. The key enzyme for the final step formation of these Lewis antigens is 1-3-fucosyltransferase. Here we report molecular cloning and functional expression of a novel Helicobacter hepaticus 1-3-fucosyltransferase (HhFT1) which shows activity towards both non-sialylated and sialylated Type II oligosaccharide acceptor substrates. It is a promising catalyst for enzymatic and chemoenzymatic synthesis of Lex, sialyl Lex and their derivatives. Unlike all other 1-3/4-fucosyltransferases characterized so far which belong to Carbohydrate Active Enzyme (CAZy, http://www.cazy.org/) glycosyltransferase family GT10, the HhFT1 shares protein sequence homology with 1-2-fucosyltransferases and belongs to CAZy glycosyltransferase family GT11. The HhFT1 is thus the first 1-3-fucosyltransferase identified in the GT11 family.

 
 
 
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