Ribosomal proteins. VII. Two-dimensional polyacrylamide gel electrophoresis for fingerprinting of ribosomal proteins.

An assembly map of 30S ribosomal subunits has been constructed. The assembly reaction is sequential and cooperative. The map may reflect the topological relationships among ribosomal proteins in the ribosomal structure.

Assembly Mapping of 30S Ribosomal Proteins from E. coli

Myosin from fast skeletal muscles consists of two large subunits (each about 200,000 daltons) and approximately four smaller subunits (in the range of 20,000 daltons). The light chains are heterogeneous in both size and charge, irrespective of the muscle type of origin. Moreover, the myosins from fast muscles of several species show a characteristic light chain pattern which is distinct from that of slower muscles.

Light chains from fast and slow muscle myosins.

The mechanism of action of protein synthesis initiation factors from rabbit reticulocytes.

Of the biogeochemical processes, denitrification has perhaps been the most difficult to study in the field because of the inability to measure the product of the process. The last decade of research, however, has provided both acetylene and 15N based methods as well as undisturbed soil core and in situ soil cover sampling approaches to implementing these methods. All of these methods, if used appropriately, give comparable results. Thus, we now have several methods, each with advantages for particular sites or objectives, that accurately measure denitrification in nature. Because of the general usefulness of the acetylene methods, updated protocols for the following three methods are given: gas-phase recirculation soil cores; static soil cores; and the denitrifying enzyme assay also known as the phase 1 assay. Despite the availability of these and other methods, denitrification budgets remain difficult to accurately establish in most environments because of the high spatial and temporal variability inherent in denitrification. Appropriate analysis of those data includes a distribution analysis of the data, and if highly skewed as is typically the case, the most accurate method to estimate the mean and the population variance is the UMVUE method (uniformly minimum variance unbiased estimator). Geostatistical methods have also been employed to improve spatial and temporal estimates of denitrification. These have occasionally been successful for spatial analysis but in the attempt described here for temporal analysis the approach was not useful.

Perspectives on measurement of denitrification in the field including recommended protocols for acetylene based methods

The ribosomal proteins of Escherichia coli. I. Purification of the 30S ribosomal proteins.

The ribosomal proteins of Escherichia coli. II. Chemical and physical characterization of the 30S ribosomal proteins.

Stoichiometry of the 30S ribosomal proteins of Escherichia coli

Publisher Summary This chapter describes a method that involves a combination of ion exchange chromatography on phosphocellulose and molecular sieve chromatography in Sephadex for the purifications of the ribosomal proteins, and presents some of the limitations of the this methodology. The purified proteins are required for detailed structural and functional analyses; however, only a relatively small number of the ribosomal proteins can be obtained in a pure state by a single chromatographic or electrophoretic fractionation step. The chapter discusses three different procedures to obtain ribosomal proteins that are free of RNA and able to reconstitute ribosomes when incubated with RNA. All of the 30 S ribosomal proteins, except two, can be obtained by a single rerun either in Sephadex or on phosphocellulose. The proteolytic enzymes that contaminate the ribosomes can produce fragments from native proteins, and these fragments will behave as though they are unique proteins. By employing well washed ribosomes, by working rapidly in the cold, and by employing esterase inhibitors, the effects of proteolytic activity can be minimized.

Charles G. Kurland

Papers

The ribosomal proteins of Escherichia coli. I. Purification of the 30S ribosomal proteins.

The ribosomal proteins of Escherichia coli. II. Chemical and physical characterization of the 30S ribosomal proteins.

Stoichiometry of the 30S ribosomal proteins of Escherichia coli

[40] Purification of ribosomal proteins from Escherichia coli☆