Candida humicola

Trimethyl arsine [593-88-4] C H As, has been identified as the toxic volatile arsenical, once known as "Gosio gas," produced by the reaction of certain molds that grow on wallpaper paste and react with inorganic arsenic compounds present in the paper. A number of microorganisms can methylate arsenic trioxide and other arsenic-containing compounds to yield trimethylarsine. These microorganisms include Scopulariopsis brevicaulis Candida humicola and Gliocladium roseum (72). 

Other biocatalysts were also used to perform the dynamic kinetic resolution through reduction. For example, Thermoanaerobium brockii reduced the aldehyde with a moderate enantioselectivity [30b,c], and Candida humicola was found, as a result of screening from 107 microorganisms, to give the (Jl)-alcohol with 98.2% ee when ester group was methyl [30dj. 

Candida humicola Candida krusei Candida mycoderma... 

After a long fallow period, other workers have recently begun to extend Challenger s arsenic biomethylation work (1-3). Cox and Alexander have studied this reaction by the mold Candida humicola (59-9/). The overall reaction may be summed up by the reaction shown in Eq. (6). Both cell extracts and whole cells of Methanobacterium strain M.o.H. converted arsenate to dimethylarsine (92). Investigations on C. humicola and other molds determined that the rate of (CH s production follows the growth rate pattern of the mold, and decreases when the mold reaches the resting phase (93). The methylated arsenic intermediates were identified by use of... 

A corresponding ThrA has been detected in a number of strictly anaerobic bacteria, and the enzyme from Clostridium pasteurianum has been purified and shown to be highly selective for L-threonine 150 [457]. A corresponding L-specific catalyst has also been purified and crystallized from cells of the yeast Candida humicola. Very recently, the latter enzyme was reinvestigated for synthetic purposes and found to have a very broad substrate tolerance for the aldehyde acceptor, notably including variously substituted aliphatic and aro-... 

The increase in PolyP level in yeast may be due to phosphate uptake stimulation. Cells of Candida humicola demonstrated a 4.5-fold increase in phosphate uptake from the medium and accumulated 10-fold more PolyP during growth at pH 5.5, when compared with growth at pH 7.5 (McGrath and Quinn, 2000). Further details on PolyP accumulation and utilization in eukaryotes are given in Chapter 8. 

It is important to note that selection of the concentrations of the uncouplers, which are inhibitory for PolyP accumulation but not for P uptake, is a difficult task. In many cases, the decrease of PolyP content in the presence of membrane-damaging agents and ionophores may be due to a break in P uptake and a lack of P, for PolyP synthesis. The latter may decrease independent of the form of P -uptake inhibition. For example, Candida humicola accumulated 10-fold more PolyP during active growth in a complete glucose-mineral salt medium, pH 5.5, than at pH 7.5. This is probably due to the high P, uptake rate from the culture medium at pH 5.5, whereas a 4.5-fold decrease in P uptake occurred at pH 7.5 (McGrath and Quinn, 2000). 

J. W. McGrath and J. P. Quinn (2000). Intracellular accumulation of polyphosphate by the yeast Candida humicola G-l in response to acid pH. Appl. Environ. Microbiol., 66, 4068-4073. 

A transferase that also has aldolase activity and has been used to prepare a number of chiral compounds is the enzyme serine hydroxymethyltransferase (SHMT) (EC 2.1.2.1). This enzyme, also known as threonine aldolase, catalyzes the physiological reaction of the interconversion of serine and glycine with pyridoxal phosphate (PLP) and tetrahydrofolate (FH4) as the shuttling cofactor of the C-1 unit. It also catalyzes a number of other reactions, some of which are independent of PLP and FH4 [72]. The SHMT-catalyzed aldolase reaction generates two stereocenters, which it does stereospecifically at the (/.-carbon, whereas it is less strict at the [l-carbon (Scheme 13). Nevertheless, this enzyme from porcine liver, Escherichia coU and Candida humicola (threonine aldolase) has been used to prepare a number of P-hydroxy-a-amino acids [73-76],... 

Threonin Aldolase Origin Candida humicola Fluka... 

Penicillium brevicaule (Scop-ulariopsis brevicaulis) Methanogenic bacteria (Meth-anobacterium strain MOH) Candida humicola, Glioclad-ium roseum and Penicillium sp. 

RW Cullen, BC McBride, and M Reimer. Induction of the aerobic methylation of arsenic by Candida humicola. Bull Environ Contam Toxicol 21 157-161, 1979. 

DP Cox, M Alexander. Effect of phosphate and other anions on trimethylarsine formation by Candida humicola. Appl Microbiol 25 408-413, 1973. 

Synthetic applications of threonine aldolase have been hampered due to the poor capacity for erythro/threo discrimination. Erythro-sdective threonine aldolase from Candida humicola has been used for the preparation of a key chiral building block in the synthesis of the immunodepressive lipid mycestericin D (Fig. 6.5.16). The conversion was purposely low to ensure a kinetic control and therefore maximizing the yield of the erythro product. 

The enzymatic aldolization of (/ )-glyceraldehyde acetonide with glycine catalyzed by L-threonine aldolase from Candida humicola gave the key intermediates for the synthesis of 3,4-dihydroxyprolines in six steps (Fujii et al. 2000). 

L-Lysine (from Z)Z.-aminocaprolactam) L-Aminocaprolactam hydrolase Candida humicola... 

Candida albicans, Candida humicola, Candida parasilopsis, Fusarium... 

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