such as cellulose xylan arabinoxylan arabinogalactan pectin hemicellulose and lignin examples of potentially such enzymes include but are not limited to amylolytic enzymes such as u03b1 amylases and u03b2 amylases or cell wall degrading enzymes such as cellulases xylanases pectinases pectin methylesterases polygalacturonases xylosidases hemicellulases glucanases or arabinosidases or proteases cutinases or lignases the present invention uses a solubility promoting compound in the extraction buffer to increase the amount of heterologously expressed enzyme found in the soluble fraction following purification it is preferred that this compound be non immunogenic so that it is not recognized by the antibodies used to detect the polypeptide of interest for example in an elisa usage of a non immunogenic compound allows the method to not require a step for the removal of a possible immunogenic compound prior to analysis of the sample by elisa examples of non immunogenic solubility promoting compounds include but are not limited to substrate degrading compounds such as an enzyme which can degrade insoluble macromolecules enzymes which can degrade insoluble macromolecules including but not limited to polysaccharides such as starch or plant cell wall components such as cellulose xylan arabinoxylan arabinogalactan pectin hemicellulose and lignin include but are not limited to amylolytic enzymes such as amylases or cell wall degrading enzymes such as cellulases xylanases pectinases pectin methylesterases polygalacturonases xylosidases hemicellulases glucanases or arabinosidases or proteases cutinases or lignases although the following examples use ground kernels the tissue from any part of the maize plant including but not limited to leaf root kernel or pollen may be used in this assay additionally this assay may be used for animal diet samples including but not limited to starter grower or finisher broiler diets or rat diet additionally this assay.