Using ubiquitin-K48A, defective in K48-mediated ubiquitin branching which targets proteins for the proteasome, and ubiquitin-K7R and methyl-ubiquitin both defective in mediating poly-ubiquitination all resulted in same pattern of mdm2-mediated GST-FOXO laddering (Fig 1c).
Collectively, these methods are used to produce a wide range of mid to high carbon chain length alcohols with single to minimal mono-methyl branching, all of which find their way into detergent manufacture.
In the methyl branch, CO2 is reduced to formate which is condensed in an ATP-dependent reaction with tetrahydrofolate (THF) to yield formyl-THF (Fig. 1).
Downstream from cooS, is a gene for the CODH accessory subunit (CooC), followed by acetyl-CoA synthetase (ACS), the ACS small and large Fe-S protein subunits, and a gene for a methyl-tetrahydrofolate corrinoid Fe-S methyl transferase, which delivers methyl groups generated in the methyl branch of the acetyl-CoA pathway to the ACS complex.
Among the first polymers to be synthesized and studied using ADMET was a precision analog of an ethylene/propylene copolymer, which may be described as polyethylene with a methyl branch on every 21st carbon.
The genome sequence of T. azotonutricium reveals that it lacks both a gene for formate dehydrogenase (which reduces CO2+H2 to formate and is the first enzyme in the methyl branch of Acetyl-CoA pathway) and a gene for methyl-THF reductase (an enzyme that generates a methyl group which is subsequently shuttled to the carbonyl branch of the pathway to form Acetyl-CoA).
In the methyl branch of the WLP, another molecule CO2 is reduced first to formate, which is then activated to formyl-THF in an ATP-dependent reaction [ 8, 9].
The latter is also corroborated by NMR study, which shows polymers with a low branch number, and isolated methyl branches predominating for high-temperature samples.
To answer this question, a series of precise methyl-branched polymers was synthesized (Table from slide 30), ranging from having a methyl branch on every fifth carbon, to having a branch on every 21st carbon, and ultimately having no branches (linear ADMET polyethylene).
Content of methyl branch increased sharply with temperature, but long branches dropped quickly.
