PubMed · 14166761
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R KILKSON. 1964. BIOLOGICAL STRUCTURE.. https://doi.org/10.1073/pnas.51.4.543
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The parameters in steady-state or rapid-equilibrium rate equations for enzyme-catalyzed reactions depend on the temperature, pH, and ionic strength, and may depend on the concentrations of specific species in the buffer. When the complete rate equation (i.e. the equation with parameters for the reverse reaction as well as the forward reaction) is determined, there are one or more Haldane relations between some of the kinetic parameters and the apparent equilibrium constant for the reaction that is catalyzed. When the apparent equilibrium constant can be calculated from the kinetic parameters, the equilibrium composition can be calculated. This is remarkable because the kinetic parameters all depend on the properties of the enzymatic site, but the apparent equilibrium constant and the equilibrium composition do not. The effects of ionic strength and pH on the unoccupied enzymatic site and the occupied enzymatic site have to cancel in the Haldane relation or in the calculation of the apparent equilibrium constant using the rate constants for the steps in the mechanism. Several simple enzymatic mechanisms and their complete rate equations are discussed.
Latin America has experienced a vigorous growth in scientific production since the 1990s, rising from 1.7% of the world's share of science publications in 1990 to 3.2% in 2000. This appears to be a consequence of increasing investment in tertiary education, especially at the doctoral level. However, such growth is not homogeneous among the nations of Latin America, being affected by many issues, such as economical power and expenses in science and technology. Biology--including comparative biochemistry and physiology (CBP)--is one of the scientific areas of tremendous growth in the continent. Thus, in order to celebrate the increasing participation of Latin America in the field of CBP, the editorial board of Comp. Biochem. Physiol. decided to organize a special volume dedicated to Latin American authors (CBP-Latin America). From May to November 2005, 52 manuscripts were submitted to CBP-Latin America from Argentina, Brazil, Chile, Cuba, Mexico, Uruguay and Venezuela. This opening issue contains the first two dozen manuscripts, highlighting the diversity of experimental approaches and the breadth and uniqueness of the biological systems available to researchers in Latin America. We hope that the CBP-Latin America project becomes a significant editorial initiative, one that will meet the goals of highlighting, integrating, and mapping CBP research in Latin America.
Most of the global human population lives in urban areas where biogeochemical cycles are controlled by complex interactions between society and the environment. Urban ecology is an emerging discipline that seeks to understand these interactions, and one of the grand challenges for urban ecologists is to develop models that encompass the myriad influences of people on biogeochemistry. We suggest here that existing models, developed primarily in unmanaged and agricultural ecosystems, work poorly in urban ecosystems because they do not include human biogeochemical controls such as impervious surface proliferation, engineered aqueous flow paths, landscaping choices, and human demographic trends. Incorporating these human controls into biogeochemical models will advance urban ecology and will require enhanced collaborations with engineers and social scientists.