Cutin hydrolysis

Remarkably, Brassica napus pollen was reported to have a 22 kDa cutinase that cross-reacted with antibodies prepared against F. solani f. pisi cutinase [134]. Although a 22 kDa and a 42 kDa protein that catalyzed hydrolysis of p-nitrophenyl butyrate were found in this pollen, only the former catalyzed cutin hydrolysis. Immunofluorescence microscopic examination suggested that the 22 kDa protein was located in the intine. Since the nature of the catalytic mechanism of this enzyme has not been elucidated, it is not clear whether this represents a serine hydrolase indicating that plants may have serine and thiol cutinases. The role of the pollen enzyme in controlling compatibility remains to be established. 

The aliphatic components of SOM, derived from various sources, tend to persist in soil (Almendros et al. 1998 Lichtfouse et al. 1998a Lichtfouse et al. 1998b Mosle et al. 1999 Poirier et al. 2000). The principal source of aliphatic materials in soil is plant cuticular materials, especially cutin, an insoluble polyester of cross-linked hydroxy-fatty acids and hydroxy epoxy-fatty acids (Kolattukudy 2001). Some plant cuticles also contain an acid and base hydrolysis-resistant biopolymer, comprised of aliphatic chains attached to aromatic cores known as cutan (Tegelaar et al. 1989 McKinney et al. 1996 Chefetz 2003 Sachleben et al. 2004). 

Acetate is known to be a good carbon source for fungi and would be expected to be the ultimate degradation product of cutin (14). The effect of acetate on the production of cutinase by the T-8 strain of F. solani was examined and compared with that of glucose. Since previous studies showed that hydrolysis of the artificial substrate p-nitrophenylbutyrate, PNB, was specifically hydrolyzed by cutinase in the T-8 strain, this activity was used to measure cutinase levels (8). Figure 1 illustrates that basal levels of cutinase activity were detected in the growth medium when T-8 was grown on... 

Purdy, R.E. and Kolattukudy, P.E. 1975. Hydrolysis of plant cutin by plant pathogens purification, amino acids composition, and molecular weight of two isoenzymes of cutinase and a nonspecific esterase from Fusarium solani f. pisi. Biochemistry, 14 2824-31. 

Cutin and suberin are lipid biopolymers of variable composition which are part of the protective outer coatings of all higher plants. Chemically, cutin and suberin are closely related polyesters composed of long-chain fatty and hydroxy fatty acid monomers. Both types of biopolymers represent labile, easily metabolizable terrigenous organic matter because they are sensitive to hydrolysis. After sedimentation, they have only a moderate preservation potential. 

Important progress has been made on the use of immobilized enzyme catalyzed polycondensation reactions to prepare a wide range of polyesters (2,83). In this book, Hunsen et al (20) describe how an inunobilized catalyst from Humilica insolens has excellent activity for polycondensation reactions between diols and diacids. The natural role of cutinases is hydrolysis of the outer cutin polyester layer on plant leaves. Cutin is made of long chain... 

Figure 8. Time course of appearance of cutinase as measured by immunochemical techniques (left) and cutinase activity as measured by -nitrophenyl butyrate hydrolysis (right) in the extracellular fluid of spore suspensions of F. solani f. sp. pisi induced with either cutin hydrolysate or purified Cie dihydroxy acid. (Reproduced with permission from Ref. 35. Copyright 1986 The National Academy of Sciences.)...

Most of the linkages in cutin are intermonomeric ester bonds with, perhaps, a small number of peroxide bridges (Kolattukudy, 1980). Methods used to break the ester linkages of cutin are also applied to suberin analysis. Techniques which have been used include alkaline hydrolysis (Eglinton and Hunne-1968), transesterification with NaOCH3-... 

Cutin and cutin hydrolysate induced the production of very small quantities of a nonspecific esterase which catalyzed the hydrolysis of a variety of small esters but not the hydrolysis of cutin. The following experimental evidence suggests that this protein might be procutinase which reaches the medium in extremely small quantities, probably as a result of a leak in the processing of the precursor (Kolattukudy, 1977b). (1) Like cutinase, the esterase contains an active serine which is involved in catalysis (Purdy and... 

Another extracellular lipase, called cutinase , is produced by the plant-pathogenic microorganism Fusarium solani pisi for the hydrolysis of cutin - a wax ester which is excreted by plants in order to protect their leaves against microbial attack [488]. The enzyme has been purified to homogeneity [489] and has been made readily available by genetic engineering [490]. Up to now it has not been widely used for biotransformations of noimatural esters, but it certainly has a potential as a useful pure lipase for complementary piuposes [491]. 

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