Enzymatic activity of cellulase adsorbed on cellulose and its change during hydrolysis

Ooshima, Hiroshi; Kurakake, Masahiro; Harano, Yoshio

doi:10.1007/bf02921752

Cited by 51 publications

(42 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Those authors found an empirically determined value of n equal to 5.3, indicative of the very strong decline in rate with increasing conversion and in general agreement with direct specific activity measurements (Nutor and Converse, 1991;Ooshima et al, 1991). Semimechanistic models with respect to substrate (only), involve concentration as the only substrate state variable and two or more solubilizing activities.…”

Section: Semimechanistic Modelssupporting

confidence: 63%

Toward an aggregated understanding of enzymatic hydrolysis of cellulose: Noncomplexed cellulase systems

Zhang

Lynd

2004

Biotech & Bioengineering

1,646

1,284

View full text Add to dashboard Cite

Information pertaining to enzymatic hydrolysis of cellulose by noncomplexed cellulase enzyme systems is reviewed with a particular emphasis on development of aggregated understanding incorporating substrate features in addition to concentration and multiple cellulase components. Topics considered include properties of cellulose, adsorption, cellulose hydrolysis, and quantitative models. A classification scheme is proposed for quantitative models for enzymatic hydrolysis of cellulose based on the number of solubilizing activities and substrate state variables included. We suggest that it is timely to revisit and reinvigorate functional modeling of cellulose hydrolysis, and that this would be highly beneficial if not necessary in order to bring to bear the large volume of information available on cellulase components on the primary applications that motivate interest in the subject. B

show abstract

Section: Semimechanistic Modelssupporting

confidence: 63%

Toward an aggregated understanding of enzymatic hydrolysis of cellulose: Noncomplexed cellulase systems

Zhang

Lynd

2004

Biotech & Bioengineering

1,646

1,284

View full text Add to dashboard Cite

show abstract

“…The extent to which cellulases can adsorb to cellulose within a lignocellulosic substrate should provide some indication of digestibility. Previous studies have observed correlations between cellulose hydrolysis rates and bound enzyme concentrations Ooshima et al, 1991). However, earlier work examining the relationship between bound cellulase and substrate digestibility have been limited by the complexity of the cellulase system Ooshima et al, 1990).…”

Section: Discussionmentioning

confidence: 99%

“…More recently, advances in cloning technologies and purification procedures have allowed the use of purified enzymes to distinguish between enzyme and substrate effects in the experiments (Eriksson et al, 2002;Palonen et al, 2004). Additionally, determining bound enzyme fractions in the reactions has become more direct and quantitative, using known extinction coefficients of the well-characterized and carefully purified enzyme components instead of indirect activity based (Meunier-Goddik et al, 1999) or colorimetric methods (Ooshima et al, 1991). However, determining the bound enzyme fraction on biomass is further complicated by the absorbance contributions of various soluble components in biomass (Ucar and Fengel, 1988).…”

Section: Discussionmentioning

confidence: 99%

Cellulase digestibility of pretreated biomass is limited by cellulose accessibility

Jeoh¹,

Ishizawa²,

Davis³

et al. 2007

Biotech & Bioengineering

460

321

View full text Add to dashboard Cite

Attempts to correlate the physical and chemical properties of biomass to its susceptibility to enzyme digestion are often inconclusive or contradictory depending on variables such as the type of substrate, the pretreatment conditions and measurement techniques. In this study, we present a direct method for measuring the key factors governing cellulose digestibility in a biomass sample by directly probing cellulase binding and activity using a purified cellobiohydrolase (Cel7A) from Trichoderma reesei. Fluorescence-labeled T. reesei Cel7A was used to assay pretreated corn stover samples and pure cellulosic substrates to identify barriers to accessibility by this important component of cellulase preparations. The results showed cellulose conversion improved when T. reesei Cel7A bound in higher concentrations, indicating that the enzyme had greater access to the substrate. Factors such as the pretreatment severity, drying after pretreatment, and cellulose crystallinity were found to directly impact enzyme accessibility. This study provides direct evidence to support the notion that the best pretreatment schemes for rendering biomass more digestible to cellobiohydrolase enzymes are those that improve access to the cellulose in biomass cell walls, as well as those able to reduce the crystallinity of cell wall cellulose.

show abstract

“…Therefore, due to the significant need for improved enzyme activity, and the demonstrated effective action of protein and surfactant-based enzyme stabilizers, we review the different mechanisms of action of these additives on cellulase stabilization. Enhanced catalytic activity of cellulase with surfactants has been reported for a variety of substrates, including steam exploded spruce, lodgepole pine [27,[30][31][32], sigma cell 100 and steam exploded poplar [32], newspaper [33], Avicel and tissue paper [34], dilute sulfuric acid pretreated creeping wild ryegrass [29], Douglas fir exploded with SO 2 and ammonia freeze explosion (AFEX) pretreated corn stover, dilute acid pretreated corn stover [26,35], lime and ammonia recycled percolation (ARP) pretreated corn stover [26], extrusion pretreated corn stover and prairie cord grass [36,37].…”

Section: Introductionmentioning

confidence: 99%

A Review of the Role of Amphiphiles in Biomass to Ethanol Conversion

2013

View full text Add to dashboard Cite

Abstract:One of the concerns for economical production of ethanol from biomass is the large volume and high cost of the cellulolytic enzymes used to convert biomass into fermentable sugars. The presence of acetyl groups in hemicellulose and lignin in plant cell walls reduces accessibility of biomass to the enzymes and makes conversion a slow process. In addition to low enzyme accessibility, a rapid deactivation of cellulases during biomass hydrolysis can be another factor contributing to the low sugar recovery. As of now, the economical reduction in lignin content of the biomass is considered a bottleneck, and raises issues for several reasons. The presence of lignin in biomass reduces the swelling of cellulose fibrils and accessibility of enzyme to carbohydrate polymers. It also causes an irreversible adsorption of the cellulolytic enzymes that prevents effective enzyme activity and recycling. Amphiphiles, such as surfactants and proteins have been found to improve enzyme activity by several mechanisms of action that are not yet fully understood. Reduction in irreversible adsorption of enzyme to non-specific sites, reduction in viscosity of liquid and surface tension and consequently reduced contact of enzyme with air-liquid interface, and modifications in biomass chemical structure are some of the benefits derived from surface active molecules. Application of some of these amphiphiles could potentially reduce the capital and operating costs of bioethanol production by reducing fermentation time and the amount of enzyme used for saccharification of biomass. In this review article, the benefit of applying amphiphiles at various stages of ethanol production (i.e., OPEN ACCESSAppl. Sci. 2013, 3 397 pretreatment, hydrolysis and hydrolysis-fermentation) is reviewed and the proposed mechanisms of actions are described.

show abstract

Enzymatic activity of cellulase adsorbed on cellulose and its change during hydrolysis

Cited by 51 publications

References 14 publications

Toward an aggregated understanding of enzymatic hydrolysis of cellulose: Noncomplexed cellulase systems

Toward an aggregated understanding of enzymatic hydrolysis of cellulose: Noncomplexed cellulase systems

Cellulase digestibility of pretreated biomass is limited by cellulose accessibility

A Review of the Role of Amphiphiles in Biomass to Ethanol Conversion

Contact Info

Product

Resources

About