Plant a-1,4-Glucan Phosphorylase [antikvár]

Hardly jnore tlian a century has elapsed since urea, a compound jjresent in living organisms, was first prepared in the laboratory by chemical synthesis by the German ciiemist Wohler. In so doing he oj)ened the field of study of the vast number of chemical compounds occurring in living organisms. (Since Wohler's work, the role, fate, formation and decomposition of a large number of these compounds have been successfully elucidated. In jjarticular, it has been established that certain biocatalysts, the enzymes, which are capable of performing reactions under extremely mild conditions (sucli as nearly neutral solution, relatively low temperature) due to their very high transfer number actually play a central role in these jirocesses. The effects of enzymes have been proved to be ])articularly specific.Just tliese specific properties have made possible their widespread use in industry. Research scientists have endeavoured to utilize enzymes under industrial conditions on the basis of their role in living organisms. At present, many problems of industrial production and use have been solved for quite a number of enzymes. Of these, the amylolytic enzymes are quite prominent. Their application offers remarkable advantages in starch degradation processes. As a comparison of the degradation operations carried out with chemical agents such as acids, the hydrolysis of glucosidic bonds is performed by amylolytic enzymes at identical proton concentrations and temperaturestimes faster than by hydrochloric acid.In addition to this extraordinary advantage, however, enzymes also have a number of unfavourable properties which limit their furtheruse in industry. (Jf these, one of the most inportant is that enzymes are very complicated protein molecules and thus extremely sensitive to external effects such as hydrogen ion concentration, temjjerature, ionic and non-ionic contaminants, etc. Another problem of industrial importance concerns the repeated use of enzyme catalysts.Recently, jnoi'e or less successful attempts have been made to overcome these difficulties by producing insoluble enzyme preparations. Though the problem of the re])eated use has been solved Iw the availability of these preparations, the sensitivity of protein molecules invariably remains high