Shape Of Amide Research Articles

Adsorption of human blood plasma on nanodiamond and its influence on activated partial thromboplastin time

Ever increasing use of engineered nanodiamond (ND) into the human blood for various biomedical studies and applications has increased the demand to thoroughly understand the interaction of NDs with blood and its effect on blood coagulation. Here, we report on the study of adsorption of human blood plasma on various sized carboxylated nanodiamonds (cNDs) using UV/visible spectroscopy and Fourier transform infrared spectroscopy (FTIR). The adsorption of human blood plasma on 5nm and 100nm sized cNDs is confirmed from UV/visible spectra. FTIR shows minor change in the shape of amide I absorption peak (1600–1700cm−1) indicating that the protein secondary structure remains unaffected for human blood plasma. The influence of cNDs on the blood coagulation has been estimated using Activated Partial Thromboplastin Time (APTT) test. The APTT test is one of the standard tests used to investigate the efficacy of the intrinsic pathways of coagulation. The APTT test results indicate that 5 and 100nm cNDs with various concentrations (10–500μg/ml) do not show delay in time when coagulation was initiated through the intrinsic pathway.

Far Ultraviolet Circular Dichroism and Infrared Absorption of Thylakoids

In suspensions of stroma freed chloroplasts, the far ultraviolet circular dichroism of the thylakoid proteins is masked by linear optical anisotropy, due to the regular stacking of thylakoids. The circular dichroism spectra of small fragments of thylakoid membranes have the shape, characteristic of a protein with consiberable α-helix content. The same is true for the vesicle like thylakoids of the purple bacterium Rhodopseudomonas spheroides, suspended in water. The turbid thylakoid suspension of the blue green alga Oscillatoria chalybea equally yields a protein spectrum, which, however, is somewhat distorted by light scattering. Corresponding results are obtained by means of infrared absorption spectroscopy. The location and shape of the amide I and amide II bands of suspensions of stroma freed chloroplasts in D2O and of solid films of chloroplasts are compatible with α-helix containing protein. It was found, that a considerable amount of the amide groups is protected against deuteration. No considerable difference is observed concerning the position and shape of amide I and amide II bands from solid films, regardless, whether the lipid absorption was eliminated either by extraction with dry acetone, or by difference spetroscopy. Disorganisation of the thylakoids by dodecyl sulfate causes only minor changes in the circular dichroism. Extraction of lipids from solid films with water containing acetone or heat denaturation results in the appearence of β-structure. Freeze dried chloroplasts are soluble in hexafluoroisopropanol. This solvent causes an increase of α-helix. Consequences of these experiments for the understanding of the molecular structure of the thylakoid membrane are discussed.