On the Origin of a Low Angle Spacing in Starch

The structure of starch granules from different botanical sources was studied by transmission electron microscopy and small‐angle X‐ray diffraction. Electron micrographs of negatively stained starch granule fragments show a rippled fibrous structure. The ripples are interpreted as being stacks of thin crystalline lamellae comprising the linear α‐(1→4) chains of the amylopectin. Optical diffraction analysis of the electron micrographs showed that the spacing of the ripples varies from 9.2 nm in potato starch to 10.4 nm in barley starch. This correlates well with the position of a Bragg peak at appr. 10 nm measured by small‐angle X‐ray diffraction. These observations indicate that the Bragg peak arises from the alternating amorphous and crystalline regions seen as ripples in the electron micrograph

Electron Microscopy and Image Analysis of the Complexes I and V of the Mitochondrial Respiratory Chain

The aim of this review is to summarize structural information on two membrane protein complexes of the eukaryotic respiratory chain. Special attention is paid to the elecron microscopy and subsequent image analysis. An extensive review on this subject has recently been published dealing with the whole respiratory chain. This contribution, however, will focus on just two enzyme complexes, i.e. the NADH:ubiquinone oxidoreductase or NADH dehydrogenase and the F0F1 ATPase or ATP synthase. This allows a more detailed discussion of many aspects not mentioned before. Moreover, new results have recently been achieved on both proteins. We will discuss structural aspects obtained by electron microscopy, and where possible functional aspects will be addressed and correlated with more general structural data. We assume that the reader is familiar with general principles of electron microscopy as well as image analysis. Therefore this review will not deal with the background of these techniques; instead, references to relevant papers will be provided.