Hypochromicity

Kinoshita, Imoto etal.11 14) synthesized other anionic models, 5 (APVP), CPVP, UPVP, TPVA, HPVA, THPVA, and 6 (AMPPVA), by the polymer reaction of N-eoupled(2-dihydrogenphosphate)-ethylderivatives of nucleic acid bases (or adenosine-5 -phosphate, AMP) with polyvinylaleohol. A, C, U, T, H, and TH denote adenine, cytosine, uracil, thymin, hypoxanthine, and theophylline, respectively. The authors reported the apparent hypochromities of 3 to 16% for many kinds of mixtures of the models and DNA or RNA, as compiled in Table 1. However, for the mixtures APVA + RNA, HPVA + RNA HPVA + DNA, THPVA + RNA, CPVA + DNA and CPVA + RNA, no hypochromicity was detected. 

Table 1. Apparent hypochromicities of anionic models of nucleic acid...

It can be seen from the figure that the electrostatic repulsive forces between the macrocations are overwhelmed, probably by hydrophobic attractive forces between their hydrophobic side groups. It should be noted that the complimentary base-base pairing is unimportant in the present case. If this is not the case, the mixtures of APVP and TPVP should show the largest hypochromicity. This, however, is not the case. The importance of the hydrophobic interactions between nucleic acid bases has been proposed by Ts o et al.I9 from thermodynamic parameters of various nucleic acid bases or nucleosides in aqueous media. 

A hypochromicity was observed between THPVP and APVP (or TPVP). Since theophylline is not a nucleic acid base and does not form hydrogen-bonding, these observations indicate that stacking-type hydrophobic forces are important. 

Copolymers of 9-vinyladenine and acrylamide, 21 (PA-A), l-vinylthymine and acrylamide, 22 (PT A) and 1-vinyluracil and maleic anhydride, 23(PU-MA) were also synthesized21. The hypochromicities with RNA were measured and compiled in Table 3. 

Peptide-type models were synthesized by Jones et a/.44, and by Takemoto etal.45). Takemoto and co-workers46 prepared polymers of 6-methylamino-, 6-di-n-propylamino-, and 6-di-n-butylamino-9-vinylpurines. They reported that these models showed no hypochromic effect on RNA in aqueous solution. 

Poly A form a complex with a 4 1 stoichiometry. The apparent hypochromicities of various mixtures are listed in Table 4. The mixtures of A12 with Poly U and of T12 with Poly A showed large hypochromicities compared with other mixtures, which suggests the importance of the hydrogen-bonding formation between complementary nucleic acid bases such as A-U and T-A. 

A hypochromicity of about 10% was, however, observed between TH12 and the polynucleotide. Furthermore, we observed a hypochromicity of 7% for the mix-... 

The important action of electrostatic forces between a cationic model and an anionic polynucleotide is clearly shown in Fig. 7. The hypochromicity sharply decreased with the ionic strength of the solution, which indicates that the base-base interactions between A12 and Poly U supported by the electrostatic attractive forces are weakened by the shielding effects of added salts. 

In a second type of thalassemia the synthesis of specific non-a-chains is impaired. The heterozygous form of 3-thalassemia is characterized by a mild hypochromic microcytic anemia, by an increased level of Hb-A2 (4 to 7 percent), and, in the majority of the cases, by an elevated Hb-F (1 to 15 percent). 

Hypochromic and bathochromic effects of the absorption spectrum of berberine on binding of all B-form DNAs (Fig. 6a). 

In order to develop compounds that can selectively target duplex RNA, Sinha et al. [ 194] studied the interaction of berberine with two different conformations of poly(rC) poly(rG) structures. Poly(rC) poly(rG) has been shown [15,215] to exist in two conformations depending on the pH of the solution, the A-form at physiological pH and the protonated form at pH 4.3. These two conformations have been characterized to have clearly defined but distinctly different circular dichroic and absorption spectral characteristics. Both the A-form and the protonated form of the RNA induced moderate hypochromic change and bathochromic shifts in the absorption maxima peaks at 344 nm and 420 nm of the alkaloid with three isosbestic points centered around 357,382 and 448 nm. Binding of berberine to both forms enhanced the fluorescence intensity, which was higher with the protonated form than with the A-from, suggesting clear differences in the nature of orientation... 

Bases stacked rather than hydrogen bonded have also been studied with quantum chemical methods [182, 244-247]. The nature of excited states in these systems has been debated and theoretical calculations are called to decide on the degree of excited state localization or delocalization, as well as the presence and energy of charge transfer states. The experimentally observed hypochromism of DNA compared to its individual bases has been known for decades [248], Accurate quantum chemical calculations are limited in these systems because of their increased size. Many of the reported studies have used TDDFT to calculate excited states of bases stacked with other bases [182, 244, 246, 247], However, one has to be cautious when us-... 

A marked interference with heme synthesis results in a reduction of the hemoglobin concentration in blood. Decreased hemoglobin production, coupled with an increase in erythrocyte destruction, results in a hypochromic, normocytic anemia with associated reticulocytosis. Decreased hemoglobin and anemia have been observed in lead workers and in children with prolonged exposure at higher PbB levels than those noted as threshold levels for inhibition or stimulation of enzyme activities involved in heme synthesis (EPA 1986a). 

Cyclized dipyrrinones such as 31 are also fluorescent with pronounced hypochromic emission, giving fluorescence at 435-505 nm from irradiation at 392-399 nm <2005JOC689>. 

Hassan et al. [39] used a sensitive color reaction method for the determination of primaquine in pharmaceutical preparation. Primaquine was treated with diazo-p-nitroaniline in acidic medium to give an orange-yellow product with an absorbance maximum at 478 nm. When the medium was made alkaline, bathochromic, and hypochromic shifts occurred the new maximum was located at 525 nm. The mean percentage recoveries for authentic samples amounted to 100 and 100.21 by the acid and alkaline procedures, respectively (P = 0.05). Both reactions could be used to determine primaquine salts in pharmaceutical preparations. The results obtained were in good agreement with those of the official methods. Recoveries were quantitative by both methods. 

Macrocytic anemias Megaloblastic anemias Vitamin B12 deficiency Folic acid deficiency anemia Microcytic hypochromic anemias Iron-deficiency anemia Genetic anomaly Sickle cell anemia Thalassemia... 

In this method, absorption spectra have been determined for methimazole (mercazolyl) in aqeuous acid and alkaline solutions. Aqeuous solutions of methimazole have an absorption band in the medium wave region with a max at 250 nm. In strong acid and alkaline media hypsochromic and hypochromic effects are observed (30). ... 

Se excess Tuva region Increasing Se content in sandy Dystrict Kastanozems, up to 2-4 ppm. Increasing Se content in plants, up to 13 ppm Deformation of hoofs, wool cover losses, hypochromic anemia. Selenium toxicity in sheep and cattle... 

Severe hypochromic microcytic anemia, responding only to vitamin B6 and not to iron, a typical symptom of B6 deficiency in many species of animals, is related to the dependence of porphyrin biosynthesis on vitamin Be, preceding the 8-aminolevulinic acid stage, at the condensation of glycine with succinate to yield a-amino- 3-ketoadipate, the immediate precursor of 8-aminolevulinic acid. 

Epileptiform fits associated with degenerative changes in the myelin sheath of peripheral nerves and spinal cord occur in B6-deficient animals. Lesions in the arteries, resembling those of human atherosclerosis, have been observed in Be-deficient monkeys. Recently, a state of Be deficiency in human infants, characterized by loss of ability to convert tryptophan to nicotinic acid, by impaired growth, convulsions, and hypochromic anemia, has been described, following omission of vitamin B6 from the diet. 

---