When concentrated dispersions of tripalmitin in Triton X-100 are added to reaction mixtures containing soluble beef liver lipase, the rate of hydrolysis of tripalmitin increases with incubation time. When the diluted substrate is aged at 37 degrees C for 3 hr before the addition of enzyme, the rate of hydrolysis is greater than the rate with freshly diluted dispersions and is constant for at le...

A new substrate, ammonium thymolphthalein monophosphate, is proposed for use in alkaline and acid phosphatase determinations. The ammonium salt shares the advantages of the sodium salt, but is a more stable substrate and results in more stable working reagents. The substrate is buffered at ph 10.1 in diethanolamine for determining alkaline phosphatase activity in 5 mm, and at pH 5.9 in citrate ...

Aminopeptidase was detected in homogenates of the free-living nematode Panagrellus redivivus with the aminoacyl substrate L-alanine-4-nitroanilide. Subcellular distribution of activity was 80% soluble and 20% membrane-associated. Aminopeptidases in the two fractions differed in affinity for Ala-4-NA, with Km's of 0.65 mM (soluble) and 2.90 mM (membrane). Specific activities (units/mg) at pH 7.8...

We have used recombinant wild-type human von Willebrand factor (VWF) and deletion mutants lacking the A1 and A3 domains, as well as specific function-blocking monoclonal antibodies, to demonstrate a functionally relevant self-association at the interface of soluble and surface-bound VWF. Platelets perfused at the wall shear rate of 1,500 s(-1) over immobilized VWF lacking A1 domain function fai...

Soluble cytochrome P-450 from bovine adrenocortical mitochrondria, capable of side chain cleavage, can be incorporated into membranes prepared by dispersion of phospholipids in aqueous buffer when cholate is added to the membrane suspension. In addition, the complete protein side chain cleavae system (i.e. including the ancillary proteins adrenodoxin and adrenodoxin reductase and the substrate ...

OBJECTIVES Multidrug efflux is a resistance mechanism that simultaneously affects susceptibility to many structurally unrelated compounds. The regulation of norA expression, which encodes the Staphylococcus aureus NorA multidrug efflux pump, is not well understood but the MgrA global regulator and the arlRS locus are involved. The expression of genes encoding proteins related to NorA, such as Q...

Vertical flow constructed wetland (VFCW) is a promising technique for removal of excess nutrients and certain pollutants from wastewaters. The aim of this study was to develop a STELLA (structural thinking, experiential learning laboratory with animation) model for estimating phosphorus (P) removal in an artificial VFCW (i.e., a substrate column with six zones) grown with umbrella papyrus (Cype...

Rat brain tyrosine hydroxylase exists in two distinct physical forms, a soluble and a membrane-bound form, The two forms are brain-region specific, with the membranebound or particulate form predominating in the striatum, an area enriched in catecholamine nerve endings and associated with a specific membrane fraction. Whereas the soluble and the particulate enzymes exhibit an identical Km for t...

Syk (p72syk) is a 72-kDa, nonreceptor, protein-tyrosine kinase that becomes tyrosine-phosphorylated and activated in B lymphocytes following aggregation of the B-cell antigen receptor. To explore the subcellular location of activated Syk, anti-IgM-activated B-cells were fractionated into soluble and particulate fractions by ultracentrifugation. Activated and tyrosine-phosphorylated Syk was foun...

Osmotically permeabilized potato (Solanum tuberosum L.) tuber slices were used to study the biosynthesis of starch under semi in vivo conditions. Criteria to distinguish the various enzymes involved in starch biosynthesis were developed based on the characteristics of the enzymes in in vitro experiments. Branching enzyme activity was inhibited at pH 8.5 or higher, while the starch synthases fun...