scholarly journals Binaphthyl-anchored antibacterial tripeptide derivatives with hydrophobic C-terminal amino acid variations

2012 ◽  
Vol 8 ◽  
pp. 1265-1270 ◽  
Author(s):  
John B Bremner ◽  
Paul A Keller ◽  
Stephen G Pyne ◽  
Mark J Robertson ◽  
K Sakthivel ◽  
...  
Keyword(s):  
Amino Acid ◽  
Staphylococcus Epidermidis ◽  
Benzyl Ester ◽  
Terminal Amino Acid ◽  
Antibiotic Resistant ◽  
Gram Positive Bacteria ◽  
Amino Acid Component ◽  
Resistant Strains ◽  
Terminal Amino

The facile synthesis of seven new dicationic tripeptide benzyl ester derivatives, with hydrophobic group variations in the C-terminal amino acid component, is described. Moderate to good activity was seen against Gram-positive bacteria in vitro. One cyclohexyl-substituted compound 2c was tested more widely and showed good potency (MIC values ranging from 2–4 μg/mL) against antibiotic-resistant strains of Staphylococcus aureus and Enterococci (VRE, VSE), and against Staphylococcus epidermidis.

scholarly journals A synthetic glucagon-like peptide-1 analog with improved plasma stability

1998 ◽  
Vol 159 (1) ◽  
pp. 93-102 ◽  
Author(s):  
U Ritzel ◽  
U Leonhardt ◽  
M Ottleben ◽  
A Ruhmann ◽  
K Eckart ◽  
...  
Keyword(s):  
Amino Acid ◽  
Plasma Insulin ◽  
Rat Plasma ◽  
Plasma Stability ◽  
Terminal Amino Acid ◽  
Terminal Amino ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1

Glucagon-like peptide-1 (GLP-1) is the most potent endogenous insulin-stimulating hormone. In the present study the plasma stability and biological activity of a GLP-1 analog, [Ser]GLP-1(7-36)amide, in which the second N-terminal amino acid alanine was replaced by serine, was evaluated in vitro and in vivo. Incubation of GLP-1 with human or rat plasma resulted in degradation of native GLP-1(7-36)amide to GLP-1(9-36)amide, while [Ser]GLP-1(7-36)amide was not significantly degraded by plasma enzymes. Using glucose-responsive HIT-T15 cells, [Ser]GLP-1(7-36)amide showed strong insulinotropic activity, which was inhibited by the specific GLP-1 receptor antagonist exendin-4(9-39)amide. Simultaneous i.v. injection of [Ser]GLP-1(7-36)amide and glucose in rats induced a twofold higher increase in plasma insulin levels than unmodified GLP-1(7-36)amide with glucose and a fivefold higher increase than glucose alone. [Ser]GLP-1(7-36)amide induced a 1.5-fold higher increase in plasma insulin than GLP-1(7-36)amide when given 1 h before i.v. application of glucose. The insulinotropic effect of [Ser]GLP-1(7-36)amide was suppressed by i.v. application of exendin-4(9-39)amide. The present data demonstrate that replacement of the second N-terminal amino acid alanine by serine improves the plasma stability of GLP-1(7-36)amide. The insulinotropic action in vitro and in vivo was not impaired significantly by this modification.

scholarly journals Modulation of Endolysin LysECD7 Bactericidal Activity by Different Peptide Tag Fusion

Biomolecules ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 440 ◽  
Author(s):  
Nataliia P. Antonova ◽  
Daria V. Vasina ◽  
Evgeny O. Rubalsky ◽  
Mikhail V. Fursov ◽  
Alina S. Savinova ◽  
...  
Keyword(s):  
Bactericidal Activity ◽  
Lytic Enzyme ◽  
Antibiotic Resistant ◽  
Gram Positive Bacteria ◽  
Highly Active ◽  
Different Types ◽  
Peptide Tags ◽  
Resistant Strains ◽  
Bacterial Outer Membrane

The use of recombinant endolysins is a promising approach for antimicrobial therapy capable of counteracting the spread of antibiotic-resistant strains. To obtain the necessary biotechnological product, diverse peptide tags are often fused to the endolysin sequence to simplify enzyme purification, improve its ability to permeabilize the bacterial outer membrane, etc. We compared the effects of two different types of protein modifications on endolysin LysECD7 bactericidal activity in vitro and demonstrated that it is significantly modulated by specific permeabilizing antimicrobial peptides, as well as by widely used histidine tags. Thus, the tags selected for the study of endolysins and during the development of biotechnological preparations should be used with the appropriate precautions to minimize false conclusions about endolysin properties. Further, modifications of LysECD7 allowed us to obtain a lytic enzyme that was largely devoid of the disadvantages of the native protein and was active over the spectra of conditions, with high in vitro bactericidal activity not only against Gram-negative, but also against Gram-positive, bacteria. This opens up the possibility of developing effective antimicrobials based on N-terminus sheep myeloid peptide of 29 amino acids (SMAP)-modified LysECD7 that can be highly active not only during topical treatment but also for systemic applications in the bloodstream and tissues.

Radioiodinated Human Fibrinogen. In Vitro Effects of Increasing Iodination

1975 ◽  
Author(s):  
B. E. Ly ◽  
P. Kierulf
Keyword(s):  
Amino Acid ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Clotting Time ◽  
Terminal Amino Acid ◽  
Human Fibrinogen ◽  
Terminal Amino ◽  
In Vitro Effects ◽  
Polypeptide Chains

Fibrinogen preparations with increasing contents of iodine, ranging from 0.2 to 20 atoms of iodine per molecule fibrinogen, were obtained with the ICl method. Aggregation and shortening of the thrombin clotting time occurred when the content of iodine exceeded 3 atoms per molecule.Upon the action of thrombin, the increase in N-terminal glycine, reflecting fibrin formation, was almost identical in native and iodinated fibrinogen. At visible gelation, however, decreased amounts of N-terminal glycine were found in heavily iodinated fibrinogen, thus indicating enhanced fibrin polymerization. N-terminal analysis of heavily iodinated fibrinogen demonstrated a deficiency in N-terminal tyrosine concomitantly with the apparance of a new N-terminal amino acid, identified as mono-iodo-tyrosine.Polyacrylamide gel electrophoresis at pH 8.9 revealed an increase in mobility following extensive iodination, but no shift in the isoelectric point was observed upon isofocusing.Neither clottability nor the behaviour of fibrinogen and its subunit polypeptide chains on SDS-gel electrophoresis was affected by iodination.

A major Litomosoides carinii microfilarial sheath glycoprotein (gp22): amino terminal sequence and immunological studies with corresponding synthetic peptides

Parasitology ◽  
1991 ◽  
Vol 103 (3) ◽  
pp. 387-394 ◽  
Author(s):  
G. Bardehle ◽  
F. J. Conraths ◽  
F. Fahrenholz ◽  
M. Hintz ◽  
D. Linder ◽  
...  
Keyword(s):  
Amino Acid ◽  
Synthetic Peptides ◽  
General Pattern ◽  
Amino Sugar ◽  
Amino Acid Sequences ◽  
Terminal Amino Acid ◽  
Amino Terminal ◽  
Terminal Amino ◽  
Amino Terminal Sequence

The major glycoprotein of the sheath of Litomosoides carinii microfilariae (gp22) was analysed for its amino acid and amino sugar composition. It is rich in proline, glutamine/glutamic acid and glycine and contains (N-acetyl)galactosamine. The N-terminal amino acid sequence was determined up to position 37. It consists of a group of 6 repeats of the pentapeptide sequence methionine-glycine-proline-glutamine-proline with two minor modifications in repeats 3–6, while the first two repeats follow the general pattern more loosely. Identical N-terminal amino acid sequences were found in at least two other sheath polypeptides (33 kDa, 39 kDa). Antisera prepared against 3 overlapping synthetic peptides corresponding to the amino terminus of gp22 recognized different epitopes. They all reacted with identical patterns of sheath polypeptides. The antisera failed to recognize antigens of 4th-stage larvae of L. carinii. In contrast, cross-reacting epitopes were detected in other parasite stages. Antisera reacted with material surrounding embryos and microfilariae in the uterus of females, and caused patchy fluorescence on the sheath of blood-derived and in vitro-released microfilariae.

scholarly journals A C-terminal amino acid substitution in the γ-chain caused by a novel heterozygous frameshift mutation (Fibrinogen Matsumoto VII) results in hypofibrinogenaemia

2010 ◽  
Vol 104 (08) ◽  
pp. 213-233 ◽  
Author(s):  
Ayumi Haneishi ◽  
Kazuyoshi Yamauchi ◽  
Fumiko Terasawa ◽  
Toshiro Ito ◽  
Fumihiro Ishida ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Substitution ◽  
Frameshift Mutation ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Glycosylation Site ◽  
Terminal Amino Acid ◽  
Ovary Cells ◽  
Terminal Amino

SummaryWe found a novel hypofibrinogenemia designated as Matsumoto VII (M-VII), which is caused by a heterozygous nucleotide deletion at position g.7651 in FGG and a subsequent frameshift mutation in codon 387 of the γ-chain. This frameshift results in 25 amino acid substitutions, late termination of translation with elongation by 15 amino acids, and the introduction of a canonical glycosylation site. Western blot analysis of the patient’s plasma fibrinogen visualised with anti-γ-chain antibody revealed the presence of two extra bands. To identify the extra bands and determine which of the above-mentioned alterations caused the assembly and/or secretion defects in the patient, 11 variant vectors that introduced mutations into the cDNA of the γ-chain or γ′-chain were transfected into Chinese hamster ovary cells. In vitro expression of transfectants containing γΔ7651A and γΔ7651A/399T (γΔ7651A with an amino acid substitution of 399Asn by Thr and a variant lacking the canonical glycosylation site) demonstrated a reduction in secretion to approximately 20% of the level seen in the transfectants carrying the normal γ-chain. Furthermore, results from other transfectants demonstrated that eight aberrant residues between 391 and 398 of the M-VII variant, rather than the 15 amino acid extension or the additional glycosylation, are responsible for the reduced levels of assembly and secretion of M-VII variant fibrinogen. Finally, the results of this study and our previous reports demonstrate that the fibrinogen γ-chain C-terminal tail (388–411) is not necessary for protein assembly or secretion, but the aberrant amino acid sequence observed in the M-VII variant (especially 391–398) disturbs these functions.

scholarly journals Energy-dependent protein folding: modeling how a protein folding machine may work

F1000Research ◽  
2021 ◽  
Vol 10 ◽  
pp. 3
Author(s):  
Harutyun Sahakian ◽  
Karen Nazarian ◽  
Arcady Mushegian ◽  
Irina Sorokina
Keyword(s):  
Molecular Dynamics ◽  
Protein Folding ◽  
Amino Acid ◽  
Dynamics Simulation ◽  
Terminal Amino Acid ◽  
Peptide Backbone ◽  
Terminal Amino ◽  
Energy Dependent

Background: Proteins fold robustly and reproducibly in vivo, but many cannot fold in vitro in isolation from cellular components. Despite the remarkable progress that has been achieved by the artificial intelligence approaches in predicting the protein native conformations, the pathways that lead to such conformations, either in vitro or in vivo, remain largely unknown. The slow progress in recapitulating protein folding pathways in silico may be an indication of the fundamental deficiencies in our understanding of folding as it occurs in nature. Here we consider the possibility that protein folding in living cells may not be driven solely by the decrease in Gibbs free energy and propose that protein folding in vivo should be modeled as an active energy-dependent process. The mechanism of action of such a protein folding machine might include direct manipulation of the peptide backbone. Methods: To show the feasibility of a protein folding machine, we conducted molecular dynamics simulations that were augmented by the application of mechanical force to rotate the C-terminal amino acid while simultaneously limiting the N-terminal amino acid movements. Results: Remarkably, the addition of this simple manipulation of peptide backbones to the standard molecular dynamics simulation indeed facilitated the formation of native structures in five diverse alpha-helical peptides. Steric clashes that arise in the peptides due to the forced directional rotation resulted in the behavior of the peptide backbone no longer resembling a freely jointed chain. Conclusions: These simulations show the feasibility of a protein folding machine operating under the conditions when the movements of the polypeptide backbone are restricted by applying external forces and constraints. Further investigation is needed to see whether such an effect may play a role during co-translational protein folding in vivo and how it can be utilized to facilitate folding of proteins in artificial environments.

scholarly journals The Nature of the N-Terminal Amino Acid Residue of HIV-1 RNase H Is Critical for the Stability of Reverse Transcriptase in Viral Particles

2014 ◽  
Vol 89 (2) ◽  
pp. 1286-1297 ◽  
Author(s):  
Guney Boso ◽  
Claes Örvell ◽  
Nikunj V. Somia
Keyword(s):  
Amino Acid ◽  
Reverse Transcriptase ◽  
Virus Particle ◽  
Amino Acid Residue ◽  
Rnase H ◽  
Terminal Amino Acid ◽  
Viral Protease ◽  
Terminal Amino ◽  
Hiv 1

ABSTRACTReverse transcriptase (RT) of human immunodeficiency virus type 1 (HIV-1) is synthesized and packaged into the virion as a part of the GagPol polyprotein. Mature RT is released by the action of viral protease. However, unlike other viral proteins, RT is subject to an internal cleavage event leading to the formation of two subunits in the virion: a p66 subunit and a p51 subunit that lacks the RNase H domain. We have previously identified RNase H to be an HIV-1 protein that has the potential to be a substrate for the N-end rule pathway, which is an ubiquitin-dependent proteolytic system in which the identity of the N-terminal amino acid determines the half-life of a protein. Here we examined the importance of the N-terminal amino acid residue of RNase H in the early life cycle of HIV-1. We show that changing this residue to an amino acid structurally different from the conserved residue leads to the degradation of RT and, in some cases, integrase in the virus particle and this abolishes infectivity. Using intravirion complementation andin vitroprotease cleavage assays, we show that degradation of RT in RNase H N-terminal mutants occurs in the absence of active viral protease in the virion. Our results also indicate the importance of the RNase H N-terminal residue in the dimerization of RT subunits.IMPORTANCEHIV-1 proteins are initially made as part of a polyprotein that is cleaved by the viral protease into the proteins that form the virus particle. We were interested in one particular protein, RNase H, that is cleaved from reverse transcriptase. In particular, we found that the first amino acid of RNase H never varied in over 1,850 isolates of HIV-1 that we compared. When we changed the first amino acid, we found that the reverse transcriptase in the virus was degraded. While other studies have implied that the viral protease can degrade mutant RT proteins, we show here that this may not be the case for our mutants. Our results suggest that the presence of active viral protease is not required for the degradation of RT in RNase H N-terminal mutants, suggesting a role for a cellular protease in this process.

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