Biomedical subjects

D F Reim

Publications and source records attributed to D F Reim.

3 recordsLinked to original sources

PubMed1994

A method for high-performance sequence analysis using polyvinylidene difluoride membranes with a biphasic reaction column sequencer.

Methods have been developed for high-sensitivity sequence analysis of proteins electroblotted onto polyvinylidene difluoride (PVDF) membranes using a Hewlett-Packard G1005A protein sequencer. This sequencer normally uses a biphasic (hydrophobic/hydrophilic) reaction column which was designed to accommodate loading and cleanup of samples from diverse solutions. However, the standard column, programs, and chemistry were not designed to accommodate PVDF, which has become a common sequencing support. In this study, a systematic evaluation of the suitability of this sequencer for analysis using PVDF bound samples was performed and included evaluation of: different wash and extraction solvents, multiple programming changes, two alternative formulations of coupling reagents, and the effect of direction for solvent and reagent deliveries. High-performance analysis of PVDF bound samples was achieved by: using a modified reaction column with an empty hydrophobic (top) half of the column module, program modifications for the reaction column and converter, substitution of ethyl acetate for the standard S2/3 extraction solvent and using prototype Version 2.0 formulations of the coupling reagents, R1 and R2. High-performance sequence analyses of experimental samples electroblotted from either 1D or 2D gels onto high-retention PVDF membranes were obtained with a 41-min cycle time, including experimental samples with initial coupling yields < 2 pmol. Routine sequencer performance was comparable to, or slightly better than, a conventional gas-phase sequencer which had been previously optimized by us for high-performance sequence analysis of electroblotted samples in the low pmol range.

Amino Acid Sequence↗

PubMed1993

High-sensitivity gas phase sequence analysis of proteins and peptides on PVDF membranes using short cycle times.

An optimized sequencer program with a cycle time of 38 min which is specifically tailored for analysis using polyvinylidene difluoride (PVDF) membranes has been developed. The program was developed using a pulsed liquid-phase instrument which was converted to gas-phase acid delivery. Gas-phase acid delivery minimized sample extraction from PVDF membranes and improved tryptophan yields in at least some cases. Other modifications which contributed to reliable high sensitivity sequencer performance included use of a Blott cartridge, substitution of ethyl acetate:heptane (1:1, v/v) instead of butyl chloride as the extraction solvent, use of a modified 100-microliters injection loop with an internal restrictor to reliably inject nearly 90% of the sample, and an HPLC gradient which resolved tryptophan from diphenylurea. These shortened cycle times were achieved at the conventional gas-phase reaction temperature. A slight increase in lag or carryover at prolines was compensated by reduced background from nonspecific acid cleavage which facilitated extended and/or high sensitivity sequencing of large proteins. Reproducible high initial and repetitive cycle yields were obtained with a wide range of experimental peptides which were electroblotted from either 1D or 2D polyacrylamide gels onto high retention PVDF membranes. Initial yields of the majority of the experimental samples analyzed with this program were less than 5 pmol. In addition, most samples with initial yields below 1-2 pmol yielded sufficient sequence information to identify the protein by comparison to protein sequence data-bases or to design oligonucleotide probes.

Amino Acid Sequence↗

PubMed1992

Microsequence analysis of electroblotted proteins. II. Comparison of sequence performance on different types of PVDF membranes.

The influence of different types of polyvinylidene difluoride (PVDF) membranes on gas phase sequence performance has been evaluated. These PVDF membranes have been classified as either high retention (Trans-Blot and ProBlott) or low retention membranes (Immobilon-P) based on their ability to bind proteins during electroblotting from gels. Initial yields, repetitive yields, and extraction efficiency of the anilinothiazolinone amino acid derivatives have been compared for several standard proteins that have been either electroblotted or loaded onto PVDF membranes by direct adsorption. These results show that the major differences in initial sequence yields between membranes arise from differences in the amount of protein actually transferred to the membrane rather than sequencer-related factors. In contrast to several previous observations from other laboratories, more tightly bound proteins do not sequence with lower initial yields and initial yields are not affected by the ratio of surface area to protein. The stronger binding on high retention PVDF membranes does not adversely affect recoveries of difficult to extract, or very hydrophobic, amino acid derivatives. Several amino acids, especially tryptophan, are actually recovered in dramatically higher yield on high retention membranes compared with either Immobilon or glass filters. At the same time, the protein and peptide binding properties of high retention membranes will frequently improve the repetitive yield by minimizing sample extraction during the sequencer cycle. Stronger protein binding together with improved electroblotting yields offer substantially improved sequence performance when high retention PVDF membranes are used.

Amino Acid Sequence↗