影像系统

The scanning tunneling microscope (STM) is a new and exciting method of direct surface analysis. Following the microscope’s first construction by Binnig and Rohrer in 1982 (1,2)—for which they won the 1986 Nobel Prize for Physics—the instrument has been extensively used to investigate the s ...

I describe herein a simple, rapid method in which double-stranded DNAs are adsorbed with little or no distortion to a film of the oligopeptide bacitracin on a glow-discharge-activated carbon. The DNAs can be readily visualized by positive staining with uranyl acetate, which forms a smooth tra ...

I describe herein a method in which pretreatment with low concentrations of uranyl acetate is used to increase the structural rigidity of protein-nucleic acid complexes, thereby substantially enhancing the information content of images obtained by high-resolution shadow-cas ...

Solution scattering is a diffraction technique that is used to study the overall structure of biological macromolecules in the solution state (1–3). Although X-rays are diffracted by electrons and neutrons are diffracted by nuclei, the physical principles are the same. Scattering views ...

Since its inception by Svedberg and coworkers in the 1920s, the analytical ultracentrifuge has provided a powerful tool in biochemistry and molecular biology, with applications ranging from simple purity checks and particle shape determinations from sedimentation velocity, i ...

One of the most fundamental parameters describing a biological macromolecule is its mol wt, M (unit g/mol), or equivalently the dimensionless “relative molecular mass,” M r. Despite this, it is not always easy to determine or, indeed, for a heterogeneous system, define. With a homogeneous system, ...

Classical light scattering, like sedimentation equilibrium in the analytical ultracentrifuge, can provide a powerful absolute method for the determination of molecular weights of macromolecules. By “classical” light scattering (as opposed to “dynamic” light scattering ) we ...

Isothermal microcalorimetry is the generic term for a range of versatile and, in principle, nondestructive techniques suitable for direct measurement of the energetics of biological processes in samples ranging from homogeneous macromolecules up to complex and heterogeneous ...

A wide variety of temperature-induced transitions in biological systems may be studied by differential scanning calorimetry (DSC). This includes such processes as thermal unfolding (denaturation) of proteins, lipid membrane phase transitions, nucleic acid ”melting,” and so fo ...

The importance of transport phenomena in biological processes is indisputable, whether they be concentration gradient driven, “active,” or Brownian diffusion processes. Light scattering can provide a rapid probe into these processes, particularly if the technique of dynamic li ...

As our knowledge of biomolecular structure becomes ever more detailed, it becomes increasingly important that we study the basic physical forces between and within macromolecules in sufficient detail, so that we might be able to understand and manipulate biological processes at the mo ...

Spectroscopy can be described as the study of the consequences of the interaction of electromagnetic radiation (light) with molecules. The most important interaction is absorption.

There is a general trend, for both instrumental and computational reasons, towards spectra recorded on single-beam or effectively singlebeam spectrometers. The results of all measurements ought to be treated as “spectra” with the analyte absorption spectrum being the difference b ...

Infrared spectroscopy was one of the earliest techniques to be used for the structural studies of polypeptides and proteins (1,2). However, a major difficulty that limited earlier studies of such biological molecules was the absorption of liquid H2O, which shows strong absorption over mu ...

Circular dichroism (CD) is the difference in the absorption of left and right circularly polarized light. It can be considered as the absorption spectrum measured with left circularly polarized light minus the absorption spectrum measured with right circularly polarized light. From ...

Unlike immunofluorescence confocal microscopy of fixed samples or microscopic surface analysis in material sciences that both involve largely indestructible samples, life-cell imaging focuses on live cells. Imaging live specimen is by definition minimally invasive imag ...

Several methods in molecular biology have now found a wide application in the morphological science domain allowing in situ detection of nucleic acids. It first became possible to visualize molecules in their natural environment 30 years ago, by adaptating nucleic acid hybridization t ...

The primary aim of enzyme cytochemistry is elucidation of intracellular localization of enzymes. Enzyme cytochemical reactions are based on the enzymatic conversion of a substrate, followed by the deposition of electron dense products at the enzyme site. So, enzyme cytochemistry re ...

The fission yeast Schizosaccharomyces pombe serves as a model system for investigating a wide variety of problems in eukaryotic cellular and molecular biology. Although probably most widely studied in relation to the control of the eukaryotic cell cycle (1) and the events of cell division ( ...

Electron microscopy (EM) has proved to be an increasingly powerful tool in the study of nucleic acids. It provides qualitative and quantitative data on the size and structure of native and experimentally manipulated DNA and RNA molecules. The electron microscope, as a tool for analyzing mole ...