A routine fitting of kinetic data to sums of exponentials with a programmable calculator

EasyBound--a user-friendly approach to nonlinear regression analysis of binding data

The introduction of non-linear regression analysis of data from pharmacological experiments has provided an enormous advantage in making it possible to analyze raw data without any mathematical transformation. However, the disadvantage has been the lack of computer programs with simple user interfaces and the ability to easily handle large amounts of data. With the aim to develop a light-weight and still powerful program we have written an application called EasyBound which is designed to be used with Microsoft Excel and hence takes advantage of the abilities of the spreadsheet application to handle large amounts of data. Focus has been on creating an easy-to-understand user interface. There are commercial programs available, but they tend to be very complex and difficult to grasp for inexperienced users. EasyBound displays original data, calculated results and graphs on the same sheet/page. The program fully implements the most powerful algorithms for non-linear regression analysis, giving results that are more accurate than using built-in iterative analysis functions of the spreadsheet application without compromising ease of use.

Double and single exponential kinetics of microtubule assembly in vitro

The kinetics of the microtubule protein assembly were studied in Mes buffer, pH 6.6, at 28 degrees C. The assembly under above conditions follow a kinetic expression containing two exponential terms. The observed two rate constants depend on protein concentration, and are on the order of 10(-2) sec-1 and 10(-3) sec-1. When CaCl2 is added to the system in low concentration, the kinetic expression becomes single exponential. The observed rate constant is independent of protein concentration and its value is 5 X 10(-3) sec-1. It is concluded that the double exponential kinetics correspond to favorable assembly conditions, probably to a high extent of nucleation, whereas the single exponential kinetics correspond to favorable assembly conditions, probably to a high extent of nucleation, whereas the single exponential kinetics is a slower process which occur under hindered assembly conditions.