ABSTRACT

In this chapter we describe recent results on using neutron,

X-ray, and light-scattering methods to analyze structural and

compositional changes due to the action of interfacially active

enzymes on a substrate of low aqueous solubility. The interfacial

mechanism poses challenges in terms of both the structural analysis

of a heterogeneous system and methods to monitor and interpret

the kinetics. Today many of these enzyme systems are used in a

range of applications, including detergency, material science, food

technology, biotechnology, and biofuels. In spite of the growing

industrial relevance, a surprisingly small number of fundamental

studies have been carried out. Here we will address mainly two

classes of important interfacially active enzymes, namely lipolytic

enzymes and cellulases. We will discuss the common features of

the two types of degradation processes, associated with the fact

that these are water-soluble enzymes acting on a substrate surface

that continuously changes due to the enzyme action. One distinctive

difference is the fate of the reaction products, which in the case of

lipolytic enzymes typically remain in the substrate matrix, whereas

the cellulose degradation products are fully soluble. In both cases

the enzymatic process causes changes to the substrate morphology

and structure. Therefore understanding these types of enzymes

requires the use of structural and surface-sensitive techniques that

can determine changes on the nanometer-length scale.