United States enzyme preparations

International Unit (IU) Ratal (kat), the true SI unit of enzyme activity Specific activity that amount of enzyme protein which brings about the conversion of 1 (Imol of substrate to product per minute under stated conditions that amount of enzyme protein which brings about the conversion of 1 mole of substrate to product per second under stated conditions. enzyme activity (as IU or kat) per mg of total protein. This is a useful measure of the purity of an enzyme preparation... 

John H. Northrop United States preparation of proteins and enzymes in... 

Wash trials are carried out by the use of soiled test pieces, eg, commonly used stains for protease evaluation are milk, blood, and grass. Commercial pre-soiled test pieces also may contain particulate matter, eg, carbon black, as part of the stain matrix. Test materials are available ready-to-use from a number of research and testing institutes in Europe and the United States, eg, Center for Testmaterials, Vlaardingen, Holland Wascherei Forschungs Institut, Krefeld, Germany EMPA, St. Gallen, Switzedand Institut voor Reinigingstechnieken TNO, Delft, Holland and Testfabrics, Middlesex, New Jersey. Alternatively, enzyme manufacturers can supply preparation procedures. 

Together with A. DiSpirito of Iowa State University, we conducted in 2007 a Mossbauer study of pMMO from M. capsulatus (Bath), aimed at determining whether the (quite active) preparations contained iron components assignable to a catalytically active site.44 Before we discuss the Mossbauer spectra, a comment about MMO catalytic activity will be in order. Biochemists have developed a propylene oxidation assay, and the MMO activity is measured in units of nmol propylene oxide/min/mg protein.45 The activities of pMMO samples investigated by us had 1500 units in whole cells, 500 units in membrane fractions (with the enzyme residing still in the membrane), and 160 units for the purified enzyme. Preparations from laboratories favoring a copper catalytic site have <20 units or no activ-ity.33,34,38 39 46 47 The above values show that catalytic activity is lost in the course of the preparation, either by loss of metals from the active site or by conformational changes not yet appreciated. 

Enzyme replacement therapy (ERT) is a therapeutic approach in which the specific enzyme that is absent or inactive in affected individuals is replaced with a functional enzyme molecule. Pancreatic enzyme preparations of porcine or bovine origin have been available in the United States for treatment of exocrine pancreatic insufficiency (EPI) in children and adults with cystic fibrosis and chronic pancreatitis since before the enactment of the Federal Food, Drug and Cosmetic Act of 1938 (ref FDA guidance on EIP April 2004). A... 

The requirements for, preparation of, and application of enzyme reference materials have been discussed extensively (134, 135, 151, 152, 153, 154, 155, 156, 157, 158). Cooperation among clinical enzvmologists in Europe and the United States over the last several years has resulted in the availability of only a few enzyme reference materials. SRM 8430 from NIST is a preparation of human erythrocyte aspartate aminotransferase in a human albumin matrix (144) certified reference material (CRM) 319 from the Community Bureau of Reference (BCR) of the Commission of the European Communities is a preparation of porcine y-glutamvltransferase in a bovine serum matrix (159). The working group of the BCR is in the process of establishing protocols and evaluating... 

T Tses for cellulase have been found (34, 35, 36), and more ambitious proposals wait only on a supply of enzyme of sufficient activity, stability, and economy. Companies like Wallerstein, Miles, and Rohm and Haas in the United States and Meiji Seika and Kinki Yakult in Japan are marketing cellulases derived from Aspergillus niger, Trichoderma viride, and other organisms. While these preparations are good, they are limited both in rate and in extent of action on solid cellulose. 

James Batcheller Sumner (1887-1955), United States. For his discovery that enzymes can be crystallized. John Howard Northrop (1891-1987), United States, and Wendell Meredith Stanley (1904-71), United States. For their preparation of enzymes and virus proteins in pure form. ... 

The amount of enzyme present or used in a process is difficult to determine in absolute terms (i.e., grams), as its purity is often low and a proportion may be in an inactive or partially active state. Other interesting parameters are the activity of the enzyme preparation and the activities of any contaminating enzymes. These activities are usually measured in terms of the activity unit U, which is defined as the amount that will catalyze the transformation of 1 omol of the substrate per minute under standard conditions. Typically, this represents 10 to 10" kg for pure enzymes and 10" to 10" kg for industrial enzyme preparations. 

James Batcheller Sumner (United States) for his discovery that enzymes can be crystallized, and John Howard Northrop (United States) and Wendell Meredith Stanley (United States) for their preparation of enzymes and virus proteins in a pure form. Summer was the first to provide concrete evidence that enzymes and proteins could be crystallized, paving the way for further research in this area. Northrop and his co-workers explored the conditions that led to formation of crystalline proteins, and mastered this art, pioneering the way for modern scientists working to crystallize proteins and viruses. Stanley demonstrated that viruses can be crystallized in the same way as proteins, and then showed that viruses are, in fact, proteins themselves. 

Several groups in the United Kingdom and two in the United States began to exploit the asymmetric features of these diverse and potentially valuable synthons in synthesis. A look at a general design for entire classes of compounds from the simple, optically pure materials provided by the enzymes make the advantages of a chemoenzymatic approach to the preparation of complex molecules clear. 

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