Secondary module length

Two additional types of methyltransferase domains have been identified in NRPSs. Yersiniabactin synthetase contains a carbon-MT domain within a Cy-MT-PCP-TE module. This domain methylates at the a-carbon of an intermediate thiazoline ring. The melithiazol synthetase utilizes an MT domain in trans to form a methyl ester at the C-terminus of the natural product. Recent in silica analysis of MT domains from secondary metabolite biosynthetic pathways has revealed the boundaries of these domains and suggests that they are typically approximately 200 amino acids in length, much shorter than previously thought. The results of this study by Mohanty and coworkers allow for the accurate prediction of N-, C-, or 0-MT activity through sequence analysis. " ... 

A variation on the method of thermal modulation is the use of a length of capillary column coated with a thick film of stationary phase. At ambient oven temperatures, this results in a retention of semivolatile analytes, which may be subsequently released to the secondary column once the trap is heated. The rapid cycling time possible with this methodology has resulted in its common application as the intermediate trap in comprehensive GC. 

Kozak, M. (1988). Leader length and secondary structure modulate mRNA function under conditions of stress. Mol. Cell. Biol. 8 2737-2744. 

A recent development of the secondary flow-enhanced membrane processes is the helical membrane module, which is characterized by a DNA helical-like spacer enveloped by polyester filter cloth with a pore size around 22 pm [31-33]. Figure 10.12 shows the schematics of the helical membrane spacers with different twisted helical angles. The main parameters of the helical membrane include the angles of twist of the spacer or membrane and the ratio of the membrane width to the length. 

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