Trinitrobenzenesulfonic acid (TNBS) may be used for quantifying dilute solutions of protein. The trinitrophenyl protein-sulfite corn plexes resulting from reaction of TNBS with protein in the presence of sulfite are highly colored and exhibit maximum spectral absorbance at 420 nm. The TNBS protein-sulfite complex is formed by a simple two.stage condensation and complexation reaction. Protein in...

serum to thaw completely during centrifugation. Further experiments have shown that protein and electrolytes can be removed rapidly from frozen serum or urine by centrifugation, at relatively low speeds with little or no visible evidence of thawing. Part of the sample (25 ml.) of urine from a nephritic dog was placed in the barrel of a '20 ml.' plastic syringe suitably plugged at the exit and f...

Traditional colorimetric protein assays such as Biuret, Lowry, and modified Lowry (U-1988) are unsuitable for colored biological samples. Here we describe an improved Lowry protein assay (U-2012), which utilizes stable reagents and offers enhanced sensitivity over the U-1988 assay. U-2012 circumvents interference from colored pigments and other substances (for example sugars) bound to perchlori...

The studies to be reported were undertaken with the idea of throwing more light on the proteins of the gastric juice. It has been found that they can be precipitated by tungstic acid at pH 3.5 and that, although heating coagulated a protein, there remained in solution a heat-uncoagulable substance which gave a positive biuret reaction. Interest in the subject was stimulated by the investigation...

The studies to be reported were undertaken with the idea of throwing more light on the proteins of the gastric juice. It has been found that they can be precipitated by tungstic acid at pH 3.5 and that, although heating coagulated a protein, there remained in solution a heat-uncoagulable substance which gave a positive biuret reaction. Interest in the subject was stimulated by the investigation...

A procedure has been developed for the measurement of total protein in cerebrospinal fluid (C SF) based on light scattering of antigen-antibody com­ plexes formed with anti-whole human serum. Twenty-five microliters of CSF are required. Precision of the method is 6.3 percent (R.S.D) and close cor­ relations are obtained with the trichloroacetic acid turbidimetric procedure. The essential condit...