Publications by authors named "Safeer Ahmad"

Herein acid phosphatase isoenzyme was extracted from the C. murale seedlings. The purification was accomplished by chromatographic techniques and passing through DEAE-cellulose and Sephadex G-100 column. The specific activity of acid phosphatase 5.75 U/mg of protein was obtained with 66 purification fold 15.8% yield and molecular mass was 29 kDa with very faint bands corresponding to 18 kDa and 14 kDa. The maximal activity at pH 5.0 and 50 °C best illustrated by first order kinetics. When temperature was raised (55 °C to 75 °C), the deactivation rate constant was increased from 0.001 to 0.014 min, while half-life was decreased from 693 to 49 min. The results of activity collected at different temperature were then used to estimate, activation energy of hydrolysis reaction (Ea = 47.59 kJmol). A high Z-value (18.86 °C min) was obtained indicating a less sensitivity towards temperatures. The residual activity examinations were carried out from 55 °C to 75 °C and assessing the Deactivation Energy (Ed 116.39 kJmol), Enthalpy change (ΔH° 113.55kJmol), Entropy change (ΔS° 110.33kJmol) and change in Gibbs free energy (ΔG° 10.02 kJmol). Taken together, thermodynamic parameters confirm the high stability of enzyme and show potential commercial applicability.

The thermal stability of purified acid phosphatase from the germinating seedlings of (Jangli halon) was investigated by studying the impact of various thermodynamic parameters [, , Δ° (enthalpy change), Δ° (free energy change), and Δ° (entropy change)] of heat treatment in the temperature range of 55-75 °C. The thermal denaturation of acid phosphatase, assessed by loss in activity, was evidently followed by first-order kinetics, which varies with time and yield during the process of denaturation. The half-life of the enzyme was 693 min at 55 °C. The (activation energy of denaturation) was calculated by the Arrhenius plot (30 kcal mol), and the -value was 17.3 °C. The various thermodynamic parameters studied were as follows: Δ°, the change in enthalpy of inactivation, was 121.93 kJ mol at 55 °C; Δ°, the change in free energy of inactivation, was 110.65 kJ mol at 55 °C; and Δ°, the change in entropy of inactivation, was 34.39 J mol k at 55 °C. This suggests that acid phosphatase activity is thermostable to long heat treatment up to 60 °C.

Background: Xeroderma pigmentosum (XP) is a rare genetic disorder, which is characterized by hyper-sensitivity to solar ultraviolet (UV) radiation. Clinical consequences of sun exposure are skin lesions and an increased risk of developing skin cancer. Genetic studies have identified eight genes associated with xeroderma pigmentosum. The proteins encoded by these genes are mainly involved in DNA repair mechanisms.

Methods: Molecular genetic characterization of patients with xeroderma pigmentosum involved positional cloning methods such as homozygosity mapping and subsequent candidate gene analysis. Mutation screening was performed through Sanger DNA sequencing.

Results And Discussion: In this case study, we report a novel protein truncating mutation in XPC associated with autosomal recessive xeroderma pigmentosum in a consanguineous Pakistani family. Genetic mapping revealed a novel single base insertion of a thymine nucleotide NM_004628.4: c.291dupT (c.291_292insT) in the second exon of XPC. The identified mutation leads to a premature stop codon (TGA) at amino acid position 98 (p.Asp98*) and thus presumably results in a truncated protein. The Xeroderma pigmentosum, complementation group C (XPC) is located on 3p25.1 and encodes a protein involved in nucleotide excision repair. The identified mutation presumably truncates all functional domains of the XPC protein, which likely results in the loss of protein function.

Conclusion: The study expands the knowledge of the mutational spectrum of XPC and is valuable for genetic counseling of affected individuals and their families.

The interaction of protonated ferrocene (PF) with chicken blood DNA (CB-DNA) has been investigated in vitro by cyclic voltammetry (CV) and UV-Vis spectroscopy as well as viscosity measurements under stomach pH and body temperature. The peak potentials shift in CV, hyperchromism in UV absorption titration, an increase in the viscosity of DNA and the results of the effect of ionic strength on the binding constant strongly support the intercalation of PF into the DNA double helix. The diffusion coefficients of PF in the presence and absence of DNA were 9.54 x 10(-11) and 1.34 x 10(-10) m2/s, respectively. The binding constant of the PF-DNA complex and the number of binding sites on a DNA molecule were calculated as being 3.07 x 10(2) M(-1) and 2.96, with the help of the Scatchard equation. An expression by Carter et al. was used for determining the binding site size (0.17 bp). The binding constant was also determined by UV absorption titration.