David H. Croll

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Covalent modification provides a mechanism for modulating molecular state and regulating physiology. A cycle of competing enzymes that add and remove a single modification can act as a molecular switch between "on" and "off" and has been widely studied as a core motif in systems biology. Here, we exploit the recently developed "linear framework" for time(More)
To examine the validity of the deuterium (D) incorporation technique for measurement of human cholesterol synthesis rates, D uptake from D2O into cholesterol was compared to sterol balance in 13 subjects each under three controlled diet settings. Subjects (age 62 +/- 3.6 yr, body weight 74 +/- 4.0 kg, BMI 27 +/- 1.4) consumed weight maintenance diets(More)
Individual selection favors that predator which can most efficiently turn its prey into increased reproductive capacity. But any species that becomes too successful in this game sows the seed of its own demise; for its progeny may be delivered into an environment where prey populations are depleted, and starvation a danger. From this danger derives a(More)
1. Cholesterol metabolism has been characterized in three species of New World primates, the cotton-top tamarin, the saddle-back tamarin, and the squirrel monkey. 2. When fed a diet containing cholesterol, the three species exhibited differing responses of plasma cholesterol levels. 3. Dietary cholesterol absorption was determined and plasma cholesterol(More)
The phase behavior and temperature-dependent molecular motions of three cholesteryl ethers (caproyl, myristyl, oleyl) and a cholesteryl carbonate (oleyl) were characterized. The properties of each ether were qualitatively similar to, but quantitatively different from, those of the corresponding cholesteryl ester. For example, cholesteryl oleyl ether(More)
The phase behavior of cholesteryl esters with triglyceride has been characterized by differential scanning calorimetry (DSC), light microscopy, and polarizing light microscopy (PLM). Temperature-dependent molecular motions determined by 13C NMR spectroscopy were correlated with thermotropic phase behavior. Two systems, cholesteryl oleate (CO) and a 3/1 w/w(More)
Peaks corresponding to the C6 protons of the four histidine residues (positions 58, 111, 123, and 182) of chicken ovomucoid have been assigned in 1H NMR spectra (360 or 470 MHz) of the native single-chain protein and of fragments of the protein corresponding to its three homologous structural domains. Comparison of the 1H NMR pH titration behavior of these(More)
The traditional approach of using homologous sequences to elucidate the role of specific amino acid residues in protein structure and function becomes more meaningful as the number of differences is minimized, with the limit being alteration of a single residue. For small proteins in solution, NMR spectroscopy offers a means of obtaining detailed(More)
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