Interactions between components of the cellulase complex of Trichoderma koningii on native substrates

Halliwell, G.; Riaz, Mohammed

doi:10.1007/bf00412270

Cited by 32 publications

(22 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Other activities detected were swelling factor (extent of swelling about 0.25), pectin lyase and pectin methylesterase. The formation of short fibres (Halliwell & Riaz, 1971) was also observed in cultures growing on MMFP. …”

Section: Enzyme Activitiesmentioning

confidence: 71%

Characteristics of Enzymes Produced by Ruminococcus flavefaciens which Degrade Plant Cell Walls

Pettipher¹,

Latham²

1979

Journal of General Microbiology

109

View full text Add to dashboard Cite

Enzyme preparations active against crystalline cellulose, marble-milled filter paper, carboxymethylcellulose (CM-cellulose), hemicellulose and xylan were obtained from cultures of Ruminococcus jlavefaciens. These preparations also contained swelling factor, pectin methylesterase, pectin lyase and low levels of aryl P-glucosidase and aryl P-xylosidase. CM-cellulase and xylanase activities were present in a high molecular weight complex, but substrate competition studies showed that different active sites were probably responsible for each activity. Analysis of products and viscosity changes during enzymic hydrolysis of CM-cellulose and xylan indicated that the most active enzymes were of the exo-1,4-Pglycosidase type. A variety of reducing sugars were released from cell walls of Lolium perenne (perennial ryegrass) by enzyme preparations.

show abstract

Section: Enzyme Activitiesmentioning

confidence: 71%

Characteristics of Enzymes Produced by Ruminococcus flavefaciens which Degrade Plant Cell Walls

Pettipher¹,

Latham²

1979

Journal of General Microbiology

109

View full text Add to dashboard Cite

show abstract

“…), various amounts of enzyme, and water to 5 ml. This concentration of cellulose (0.6 mg/ml) was used so that cellulolysis would proceed to completion (7,8,12,14) within a relatively short time with minimum interference from products (12).…”

Section: Sources Of Enzymes a Crude Cellulase Preparationmentioning

confidence: 99%

Saccharification of Complex Cellulosic Substrates by the Cellulase System from Clostridium thermocellum

Johnson

Sakajoh

Halliwell

et al. 1982

Appl Environ Microbiol

Self Cite

315

View full text Add to dashboard Cite

True cellulase activity has been demonstrated in cell-free preparations from the thermophilic anaerobe Clostridium thermocellum . Such activity depends upon the presence of Ca 2+ and a thiol-reducing agent of which dithiothreitol is the most promising. Under these conditions, native (cotton) and derived forms of cellulose (Avicel and filter paper) were all extensively solubilized at rates comparable with cellulase from Trichoderma reesei . Maximum activity of the Clostridium cellulase was displayed at 70°C and at pH 5.7 and 6.1 on Avicel and carboxymethylcellulose, respectively. In the absence of substrate at temperatures up to 70°C, carboxymethylcellulase was much more unstable than the Avicel-hydrolyzing activity.

show abstract

“…It was subsequently shown that some exoglucanases could also attack from the reducing end. Despite our inability to find an enzyme which could induce “amorphogenesis” to a cellulosic substrate, the proposed synergistic C 1 −C X interaction model was adapted to suggest an endo‐exo interaction that results in more than just the additive interaction of the component cellulases (28, 29, 62, 196).…”

Section: Introductionmentioning

confidence: 99%

Substrate and Enzyme Characteristics that Limit Cellulose Hydrolysis

Mansfield

Mooney

Saddler

1999

Biotechnology Progress

754

509

View full text Add to dashboard Cite

The ability and, consequently, the limitations of various microbial enzyme systems to completely hydrolyze the structural polysaccharides of plant cell walls has been the focus of an enormous amount of research over the years. As more and more of these extracellular enzymatic systems are being identified and characterized, clear similarities and differences are being elucidated. Although much has been learned concerning the structures, kinetics, catalytic action, and interactions of enzymes and their substrates, no single mechanism of total lignocellulosic saccharification has been established. The heterogeneous nature of the supramolecular structures of naturally occurring lignocellulosic matrices make it difficult to fully understand the interactions that occur between enzyme complexes and these substrates. However, it is apparent that the efficacy of enzymatic complexes to hydrolyze these substrates is inextricably linked to the innate structural characteristics of the substrate and/or the modifications that occur as saccharification proceeds. This present review is not intended to conclusively answer what factors control polysaccharide biodegradation, but to serve as an overview illustrating some of the potential enzymatic and structural limitations that invariably influence the complete hydrolysis of lignocellulosic polysaccharides. IntroductionDespite the extensive amount of research undertaken over the last few decades, our understanding of how enzymes completely hydrolyze lignocellulosic substrates is still far from comprehensive or complete. Past work has indicated the complexity of the substrate and the need for many different enzymes before these substrates can be effectively and completely hydrolyzed. However, the deceptive simplicity of the repeating -1-4 linking cellobiose unit is not indicative of the complex arrangement of the substrate at the fibril, fiber, and wood/pulp levels. Similarly, although tools such as molecular biology and protein engineering have helped elucidate the role of some of the enzymes in the synergistic attack of lignocellulosic substrates, our understanding of basic mechanisms such as enzyme regulation, kinetics, and the extent of true synergism is still lacking. As a result, an important aspect of much of the research to date has been to ascertain the limiting factors involved in the decreased hydrolysis rate as time progresses. These factors have traditionally been divided into two groups: those which relate to the structure of the substrate and those related to the mechanisms and interactions of the cellulase enzymes.Various model cellulose substrates have been used for the purpose of studying the mechanism of action and interaction of individual cellulase enzymes and the effect of substrate characteristics, such as degree of polymerization and crystallinity, on the rate and efficiency of enzymatic hydrolysis. These include Avicel, solka floc, filter paper, cotton, valonia cellulose, phosphoric acid swollen cellulose, bacterial microcrystalline cellulose (BMCC) and solu...

show abstract

Interactions between components of the cellulase complex of Trichoderma koningii on native substrates

Cited by 32 publications

References 20 publications

Characteristics of Enzymes Produced by Ruminococcus flavefaciens which Degrade Plant Cell Walls

Characteristics of Enzymes Produced by Ruminococcus flavefaciens which Degrade Plant Cell Walls

Saccharification of Complex Cellulosic Substrates by the Cellulase System from Clostridium thermocellum

Substrate and Enzyme Characteristics that Limit Cellulose Hydrolysis

Contact Info

Product

Resources

About