Purification by affinity chromatography of a membrane dicarboxylate binding protein from Bacillus subtilis

1981 ◽  
Vol 27 (8) ◽  
pp. 795-800 ◽  
Author(s):  
William W. Kay

Membrane vesicles of Bacillus subtilis W23 actively transport the C4 and C5 dicarboxylates of the tricarboxylate cycle by system(s) of relatively high affinity for their requisite substrates (Km 4–53 μM). Glutamate and succinate binding activities were readily solubilized from membrane vesicles by nonionic detergents, particularly by Lubrol WX. From this extract, glutamate binding activity was highly enriched by affinity chromatography on phloroglucinol-expanded Sepharose-6B to which L-aspartate was coupled via divinylsulfone. Another protein (41 000 molecular weight), which bound both L-glutamate and L-malate, was purified from affinity columns to which either L-glutamate or L-malate had been coupled via bisdiglycidyl ether. This protein bound labelled L-malate as well as L-glutamate with affinities similar to those seen with membrane vesicles (Kd's 8 μML-malate and 52 μML-glutamate).

1982 ◽  
Vol 60 (8) ◽  
pp. 798-803 ◽  
Author(s):  
Mike Francis ◽  
Mamoru Watanabe

A steroid-binding protein obtained from the supernatant of the final wash from the preparation of membrane vesicles was purified severalfold to near homogeneity. The protein binds C18 and C19 steroids but has the highest affinity for androstenedione (Kd = 1.6 × 10−10 M). The molecular weight is 51 000 – 58 000. Binding activity is slightly inhibited by Cu2+, Ca2+, and Mg2+ and completely inhibited by Zn2+. The protein has no detectable steroid degradative activity. Analysis of androstenedione binding revealed negative cooperativity of binding for this ligand and may indicate a regulatory function for this protein. It is postulated that this protein binds the steroid after testosterone is converted to androstenedione.


1984 ◽  
Vol 218 (3) ◽  
pp. 805-810 ◽  
Author(s):  
J G Haddad ◽  
M A Kowalski ◽  
J W Sanger

The human plasma protein binding vitamin D and its metabolites (Gc globulin; group-specific component) has been isolated from human plasma by column affinity chromatography on gels to which monomeric actin was covalently attached. Rabbit skeletal-muscle G-actin was covalently coupled to amino-agarose gels before the application of human plasma. At actin/protein molar ratios of 4-8:1, excellent recovery (approximately 58%) of purified binding protein was achieved. After 0.75 M-NaCl washes, the binding protein was eluted from the columns in 3 M-guanidinium chloride, dialysed and analysed. These eluates contained the binding protein as 34-100% of the total protein, reflecting a 130-fold average purification in this single step. In the presence of Ca2+, gelsolin (another plasma protein that binds actin) was apparently retained by the affinity column, but this was prevented by chelation of plasma Ca2+. The actin affinity step also was effective in the isolation of the binding protein from rat, rabbit and chicken plasma, as indicated by autoradiographs of purified fractions analysed by gel electrophoresis after incubation with 25-hydroxy[26,27-3H]cholecalciferol. Further isolation by hydroxyapatite chromatography yielded a purified binding protein which displayed characteristic binding activity toward vitamin D metabolites and G-actin, and retained its physicochemical features. This brief purification sequence is relatively simple and efficient, and should prove to be useful to investigators studying this interesting plasma protein.


1985 ◽  
Vol 5 (8) ◽  
pp. 683-688 ◽  
Author(s):  
Jan Holm ◽  
Steen Ingemann Hansen ◽  
J⊘rgen Lyngbye

High-affinity binding of [3H]folate to supernatant from homogenized human leukocytes containing large amounts of binding protein displayed apparent positive cooperativity. The DEAE-Sepharose® CL-6B chromatographic profile of the supernatant at pH 6.3 contained a major peak of folate binding (Mr approx. 25 000) in the front effluent and a smaller more acidic peak (Mr approx. 25 000) that emerged after a rise in NaCl from 30 mmol/l to 1 mol/l. Triton X-100 solubilized ceil sediment from the leukocyte homogenate contained some high-affinity folate binding activity (Mr approx 25 000), typically 5–10% of the total binding activity.


1998 ◽  
Vol 180 (18) ◽  
pp. 4967-4973 ◽  
Author(s):  
Lotte B. Pedersen ◽  
Thomas Murray ◽  
David L. Popham ◽  
Peter Setlow

ABSTRACT The pbp gene (renamed dacC), identified by the Bacillus subtilis genome sequencing project, encodes a putative 491-residue protein with sequence homology to low-molecular-weight penicillin-binding proteins. Use of a transcriptional dacC-lacZ fusion revealed thatdacC expression (i) is initiated at the end of stationary phase; (ii) depends strongly on transcription factor ςH; and (iii) appears to be initiated from a promoter located immediately upstream of yoxA, a gene of unknown function located upstream of dacC on the B. subtilis chromosome. A B. subtilis dacCinsertional mutant grew and sporulated identically to wild-type cells, and dacC and wild-type spores had the same heat resistance, cortex structure, and germination and outgrowth kinetics. Expression ofdacC in Escherichia coli showed that this gene encodes an ∼59-kDa membrane-associated penicillin-binding protein which is highly toxic when overexpressed.


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