The United States of America As Represented by the Secretary of

William L Stanley

Merle S Masri

Virginia G Randall

Leonard Jurd

A Douglas King, Jr

Bock G Chan

Carl A Elliger

Glenn G Watters

Insolubilized but active enzymes are prepared in a variety of ways. In one embodiment of the invention an aqueous solution of an enzyme is mixed with chitosan dissolved in water at pH 3-7 and an insolubilized product is precipitated therefrom by addition of alkali or a source of sulfate ions. Another embodiment of the invention involves contacting solid chitosan sulfate with an aqueous solution of the enzyme to be immobilized. In yet another embodiment of the invention solid chitosan is cross-linked with a polyfunctional cross-linking agent and then contacted with an aqueous solution of an enzyme. Enzymes insolubilized in accordance with the invention retain a substantial part of their original activity.

Method for insolubilizing enzymes on chitosan

Insolubilized but active enzymes are prepared by mixing an aqueous solution of the enzyme with a modified phenolic polymer. The phenolic polymer is modified by introducing into the polymer chain either aldehyde groups or diazonium salt groups. The so-produced enzyme products retain a substantial part of the original enzyme activity.

Insolubilization of enzymes on modified phenolic polymers

Insolubilized but active enzymes are prepared by mixing an aqueous solution of the enzyme with an aqueous solution of chitosan and then adding a polyfunctional cross-linking agent to form a gel. The so-produced gel is reacted with a reducing agent to form a granular insolubilized enzyme, which has retained a substantial part of its original activity.

Insolubilized but active enzymes are prepared by mixing an aqueous solution of the enzyme with reduced keratin-containing material. The invention is particularly useful for insolubilizing sulfhydryl-containing enzymes such as urease.

Immobilization of enzymes on keratin

Tyrosine and 3,4-dihydroxyphenylalanine (DOPA) are separated from a mixture thereof by applying the mixture to a polymer of p-vinylbenzene boronic acid, and then serially eluting the tyrosine and DOPA.

Process for separating DOPA from tyrosine

Substances which are subject to microbial spoilage are preserved by addition of a cinnamyl phenol, e.g., 2-cinnamyl-phenol, 4-cinnamyl-phenol, 2-methoxy-4-cinnamyl-phenol, 2-cinnamyl-5-methoxy-quinol, etc.

Mixture of cinnamylphenols and normally spoilable substance

Substances which are subject to microbial spoilage are preserved by addition of a cinnamyl phenol, e.g., 2-cinnamylphenol, 4-cinnamyl phenol, 2-methoxy-4-cinnamyl-phenol, 2-cinnamyl-5-methoxy-quinol, etc.

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El Cerrito, CA, United States of America

William L Stanley