MCO Production and Expression Systems

How do the recombinant expression system and the host affect the mature protein stmcture and function Do posttranslational modifications (e.g., glyco-sylation, pre- and pro-polypeptide processing) need to be addressed  

What contaminants need to be removed from the cmde protein preparation What is the final scale for purification  

What is the final intent for the enzyme (e.g., analytical characterization or practical apphcations)  

MCO enzymes for EFC technology have eome Irom a wide variety of plant, fungal, bacterial, and even human sources. To best deseribe and understand these expression systems, the application of several published expression systems will be detailed. The majority of MCOs used for cathodie redox reaetions in EFC studies have been laceases, AOx, and BOx their heterologous expression wiU be outlined in the next seetion, with a brief summary of other MCOs sueh as eemloplasmin (CP) and bacterial MCOs. 

Because of low levels of protein synthesis and undesirable preparation requirements, plant and fungal laceases are often recombinantly expressed using recombinant yeast systems. An exhaustive list and description of heterologously produced laceases can be found in Ref. [13]. Saccharomyces cerevisiae and Pichia pastoris are two common hosts for laccase expression. The yeasts have advantage over native sources because they will grow to high density in liquid cultures and stiU complete eukaryote-specific posttranslational modifications [13]. 

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