The dependence of the specific activity of urease upon the apparent absolute enzyme concentration

If the activity of an enzyme preparation is determined under conditions in which a further increase in substrate concentration is without demonstrable effect, all other factors being held constant, it is ordinarily assumed that the specific activity of the enzyme, expressed in terms of arbitrary units per unit weight of the enzyme, is independent of the absolute enzyme concentration (1, 2). However, with urease solutions stabilized with hydrogen sulfide or cysteine (1) we have observed that the specific activity of a given urease preparation, when determined under the above conditions, increases with decreasing apparent enzyme concentration over a wide range of concentrations and that this increase in specific activity proceeds with a measurable velocity at temperatures above 15°. This phenomenon was observed with crude urease preparations, such as jack bean meal, and with two, three, and seven times recrystallized urease. Since little or no difference was observed in the behavior of three and seven times recrystallized urease, the data presented in this paper are limited to those obtained with thrice recrystallized preparations. Urease activity was determined by a modification of the procedure described by Van Slyke and Cullen (3). The precision of the modified procedure was ±2 to 3 per cent

WHAT IS "THE BASIS," HOW IS IT MEASURED, AND WHY DOES IT MATTER?

Basis behavior is generally considered to be the major determinant of hedging success or failure. In the course of our work as contract designers for Chicago Mercantile Exchange Inc., we have come to the conclusion that there are many misconceptions and incorrect statements made about "the basis" among practitioners and academics alike. Our work suggests that basis values, how they are measured, what they represent and how they are interpreted may differ widely from one commodity contract to another due to differences in the specifications of the underlying futures market, as well as differences in the structure of the underlying cash market.Marketing,

A Study of Faculty Resources for the Purpose of Improving Curriculum Planning

Teachers often have interests, skills, and specialties that can enrich their students’ experience by extending their learning beyond the traditional confines of grade-level education. This paper proposes surveying faculty about their personal hobbies and interests, and creating a reference resource that will help school administrators and teachers access one another’s personal interests in order to enrich their curricula. The researcher created two surveys. The first was a simple questionnaire focusing on teachers’ resource/curriculum needs. Out of 225 teachers, 75 completed and returned the first questionnaire. This data was used to create a more detailed second questionnaire, which attempted to gather data about teachers’ special interests in order to fulfill teachers’ expressed needs. Out of 225 teachers, 100 responded. The results from the second questionnaire were then used to create a “Faculty Resource Manual” which was distributed to all teachers within the school district

Leslie Population Estimate for a Large Lake

The accuracy of a population estimate made by the Leslie removal method was evaluated for adult northern pike (Esox lucius) in a 288-hectare lake. The Leslie estimate of 6,290 fish was within 1% of that obtained from direct enumeration