Color reaction

About: Color reaction is a research topic. Over the lifetime, 1194 publications have been published within this topic receiving 19579 citations.

New peroxidase-substrate 3,5-di-tert-butylcatechol for colorimetric determination of blood glucose in presence of Prussian Blue-modified iron oxide nanoparticles

Abstract: Prussian Blue-modified iron oxide (PB-Fe 2 O 3 ) nanoparticles (NPs) have been demonstrated to exhibit peroxidase-like activity through catalytic oxidation of the peroxidase substrate 3,5-di-tert-butylcatechol (3,5-DTBC) in the presence of H 2 O 2 , producing a yellow-colored solution. Kinetic analysis of the data indicates typical Michaelis–Menten catalytic behavior. On the basis of the catalyzed color reaction, we have developed a simple, cheap, highly sensitive and selective colorimetric method for the detection and estimation of glucose in phosphate buffer solution of pH 7.0. 3,5-DTBC has been to be a better reagent for the estimation of glucose compared with common peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) in that a phosphate buffer solution of pH 7.0 is optimum for the performance of glucose oxidase (GOx) activity as well as oxidation of 3,5-DTBC by the liberated hydrogen peroxide in a single step. Using PB-Fe 2 O 3 NPs and 3,5-DTBC/glucose–GOx system, glucose can be estimated in the linear range 1–80 μM with a detection limit of 0.16 μM. Based on this single-step reaction, human blood glucose level can be monitored conveniently.

Study of a Lipohydroperoxide Breakdown Factor in Soy Extractsa

Abstract: SUMMARY The rapid decrease in linoleic acid hydroperoxides observed with relatively high levels of soy flour extract was investigated. The hydroperoxide breakdown factor can be eliminated by high-temperature short-time treatment of soy extracts. The addition of KCN to reaction mixtures caused a partial inhibition of the breakdown factor activity. Variations in hydroperoxide breakdown activity with variations in pH and reaction time were studied. A possible optimum at pH 8-9 was indicated. Qualitative evidence for the presence of a lipohydroperoxidase was obtained with well-known reagents that produce a specific color reaction with peroxidases.

Direct estimation of lysine in corn meals by the ninhydrin color reaction.

Abstract: Since the discovery that opaque-2 (o2) and floury-2 (fl2) mutants of corn have grains high in lysine (Mertz et al., 1964; Nelson et al., 1965), extensive breeding programs have been underway to develop suitable high-lysine hy­ brids. The recent discovery of modifier genes has permit­ ted development of high-lysine corns having vitreous ker­ nels resembling normal dent com in contrast to the floury characteristics of regular o2 and fl2 mutants (Bauman and Aycock, 1970). Breeding programs for high-lysine corn, especially of the vitreous type, have been handicapped by the lack of a simple rapid a.ssay method for lysine content. The use of colorimetric and enzymatic methods, gas and ion-exchange chromatography, and methods of analy­ sis for different proteins has been reviewed by Paulis et al. (1974a,b) and Concon (1972). However, each of these methods for evaluating lysine content lacks either sim­ plicity or accuracy. Recently, !'vlertz et al. (1975) used the ninhydrin re­ agent upon extracts of individual kernels of several cereal grains to detect differences in free amino acid levels. Since high-lysine lines contain much higher levels of free amino acids (Mertz et al., 1975), use of the ninhydrin color reaction permitted them to distinguish normal and high-lysine corns. Prior to the report of their findings, work at this laboratory established that the ninhydrin reaction of total amino groups in the kernel can be corre­ lated with the lysine content of corn. However, if the free amino acids are removed from the meal of corn or other grains, the ninhydrin reagent can be used for a quantitative estimate of lysine content in protein in the grain samples. The production of color by ninhydrin reaction with aand E-amino groups in the grain proteins is facilitated by use of special solvent systems. The reaction is easy to perform and requires only small quantities of sample (10-20 mg).