The tryptophanyl fluorescence decays of two myoglobins, i.e., sperm whale and tuna myoglobin, have been examined in the frequency domain with an apparatus which utilizes the harmonic content of a mode-locked laser. Data analysis was performed in terms of continuous distribution of lifetime having a Lorentzian shape. Data relative to sperm whale myoglobin, which possesses two tryptophanyl residu...

Free norepinephrine, epinephrine, and dopamine are determined in urine after purification on a small ion-exchange column and concentration on alumina. The catecholamines are separated by reversed-phase ion-pair chromatography and are quantitated by measuring their native fluorescence (lambda ex 285 nm, lambda em 305 nm). The internal standard is dihydroxybenzylamine. Within-day CVs for the comp...

Plasma catecholamines were fluorometrically determined by a modification of the standard alumina-trihydroxyindole method in which radioactive tracer catecholamines are used to follow the chromatographic behavior of the endogenous catecholamines on alumina. This modification permits appropriate fluorometry of that portion of the eluate with the highest concentration of catecholamines, because in...

Usingdifferent conditions for incubation and fluorometry with 4-methylumbelliferylglycosides as substrates, we demonstratedthe presence ofacida-glucosidase, “renal” a-glucosidase, N-acetyl--D-glucosaminidase A, and N-acetyl-f3-o-glucosaminidase B in freshly drawn normal human serum. The acid a-glucosidase enzymatic activity was determined at pH 4.0 in 0.1 mol/L Tris reagent, whereasthe renal is...

Dynamic aspects of the heme-binding site of myoglobins derived from two phylogenetically distant species, namely sperm whale and bluefin tuna, have been investigated by studying steady-state and time-resolved emission properties of 2-p-toluidinyl-6-naphthalene sulfonic acid (TNS) apomyoglobin conjugates. Multi-frequency phase and modulation fluorometry data indicate that charge movements occur ...

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Large-conductance voltage- and calcium-dependent potassium channels (BK, "Big K+") are important controllers of cell excitability. In the BK channel, a large C-terminal intracellular region containing a "gating-ring" structure has been proposed to transduce Ca(2+) binding into channel opening. Using patch-clamp fluorometry, we have investigated the calcium and voltage dependence of conformation...