The imidazole/imidazolium ring of histidine is aromatic at all pH values. The N3-H tautomer, shown in the figure above, is protonated on the #3 nitrogen, farther from the amino acid backbone bearing the amino and carboxyl groups, whereas the N1-H tautomer is protonated on the nitrogen nearer the backbone. The remaining proton of the imidazole ring can reside on either nitrogen, giving rise to what are known as the N1-H or N3-H tautomers. Above pH 6, one of the two protons is lost. The positive charge is equally distributed between both nitrogens and can be represented with two equally important resonance structures. The resulting imidazolium ring bears two NH bonds and has a positive charge. Thus, below a pH of 6, the imidazole ring is mostly protonated (as described by the Henderson–Hasselbalch equation). The conjugate acid (protonated form) of the imidazole side chain in histidine has a p K a of approximately 6.0. 2.3 Conversion to other biologically active amines.1 Properties of the imidazole side chain.'Skeleton' is part of the collection of apps for the study of human anatomy '3D Atlas of Anatomy', new apps and updates are being developed.

The anatomical terms can be shown in two languages simultaneously.The language can be selected directly from the interface of the app.The anatomical terms and the interface are available in 11 languages: Latin, English, French, German, Italian, Portuguese, Russian, Spanish, Chinese, Japanese and Korean.Hide / Show interface, ideal for use on smartphones.Interactive Pin allow visualization of the term relative to every anatomical detail.Intelligent rotation, automatically moves the centre of rotation for easier navigation.Division by regions for a clear and immediate visual of each structure.Rotate and Zoom every model in the 3D space.Surfaces of the skeleton with high resolution textures up to 4K.'Skeleton' is a useful tool for students of medicine and physical education, for physicians, orthopedists, physiatrists, physiotherapists, kinesiologists, paramedics, nurses and athletic trainers. 'Skeleton - 3D Atlas of Anatomy' is a next generation anatomy atlas in 3D which gives you availability of interactive highly detailed anatomical models!Įach bone of the human skeleton has been reconstructed in 3D, you can rotate and zoom in on each model and observe it in detail from any angle.īy selecting models or pins you will be shown the terms related to any specific anatomical part, you can select from 11 languages and show the terms in two languages simultaneously. What does Skeleton 3D Anatomy do? In-app purchases to unlock all body regions (Full Version)

3d interactive human skeleton