scholarly journals Charge reversal of ammodytoxin A, a phospholipase A2-toxin, does not abolish its neurotoxicity

2000 ◽  
Vol 352 (2) ◽  
pp. 251-255 ◽  
Author(s):  
Petra PRIJATELJ ◽  
Alenka ČOPIČ ◽  
Igor KRIŽAJ ◽  
Franc GUBENŠEK ◽  
Jože PUNGERČAR
Keyword(s):  
Amino Acid ◽  
Phospholipase A2 ◽  
Binding Affinity ◽  
Positive Charge ◽  
Basic Amino Acid ◽  
Terminal Region ◽  
Single Site ◽  
Amino Acid Residues ◽  
Multiple Site ◽  
Charge Reversal

The positive charge concentrated at the C-terminal region of ammodytoxin (Atx) A, which is involved in presynaptic toxicity, has been reversed. A six-site mutant of AtxA (K108N/K111N/K127T/K128E/E129T/K132E, where K108N = Lys108 → Asn etc.) was prepared, in which five out of seven C-terminal basic amino acid residues were substituted with neutral or acidic ones. The mutant was approximately 30-fold less lethal, but still neurotoxic. Consistent with this, its binding affinity for the neuronal receptors decreased by only a factor of five. Additionally, a single-site mutant of AtxA was prepared, with substitution at only one position (K127T) out of six mutated in the six-site mutant. Its toxicity indicated that most, if not all, of the six mutated residues partially contribute to the decreased lethality of the multiple-site mutant.

scholarly journals Correlation of the lipolytic action of synthetic peptides with their structures: Importance of acidic and basic amino acid residues in the N-terminal region.

1988 ◽  
Vol 52 (5) ◽  
pp. 1165-1172
Author(s):  
Hiroshi MASUNO ◽  
Hisako NAKAMURA ◽  
Takeshi OHARA ◽  
Hiromi YAMASHITA ◽  
Kumiko FUNAKI ◽  
...  
Keyword(s):  
Amino Acid ◽  
Synthetic Peptides ◽  
Basic Amino Acid ◽  
Terminal Region ◽  
Amino Acid Residues ◽  
Lipolytic Action

scholarly journals Primary- and secondary-structural analysis of a unique prokaryotic metallothionein from a Synechococcus sp. cyanobacterium

1988 ◽  
Vol 251 (3) ◽  
pp. 691-699 ◽  
Author(s):  
R W Olafson ◽  
W D McCubbin ◽  
C M Kay
Keyword(s):  
Amino Acid ◽  
Metal Binding ◽  
Helical Structure ◽  
Basic Amino Acid ◽  
Cysteine Residues ◽  
Amino Acid Residues ◽  
C Terminus ◽  
Empirical Relations ◽  
Heavy Metal Binding ◽  
Synechococcus Sp

Biochemical and physiological studies of Synechococcus cyanobacteria have indicated the presence of a low-Mr heavy-metal-binding protein with marked similarity to eukaryotic metallothioneins (MTs). We report here the characterization of a Synechococcus prokaryotic MT isolated by gel-permeation and reverse-phase chromatography. The large number of variants of this molecule found during chromatographic separation could not be attributed to the presence of major isoproteins as assessed by amino acid analysis and amino acid sequencing of isoforms. Two of the latter were shown to have identical primary structures that differed substantially from the well-described eukaryotic MTs. In addition to six long-chain aliphatic residues, two aromatic residues were found adjacent to one another near the centre of the molecule, making this the most hydrophobic MT to be described. Other unusual features included a pair of histidine residues located in repeating Gly-His-Thr-Gly sequences near the C-terminus and a complete lack of association of hydroxylated residues with cysteine residues, as is commonly found in eukaryotes. Similarly, aside from a single lysine residue, no basic amino acid residues were found adjacent to cysteine residues in the sequence. Most importantly, sequence alignment analyses with mammalian, invertebrate and fungal MT sequences showed no statistically significant homology aside from the presence of Cys-Xaa-Cys structures common to all MTs. On the other hand, like other MTs, the prokaryotic molecule appears to be free of alpha-helical structure but has a considerable amount of beta-structure, as predicted by both c.d. measurements and the Chou & Fasman empirical relations. Considered together, these data suggested that some similarity between the metal-thiolate clusters of the prokaryote and eukaryote MTs may exist.

scholarly journals Thermal Behavior of Basic Amino Acid Residues of Muscle Protein during the Incubation of Fish and Poultry Minces

1998 ◽  
Vol 64 (1) ◽  
pp. 121-124 ◽  
Author(s):  
S. M. Zahangir Hossain ◽  
Tomomi Ito ◽  
Satoshi Kanoh ◽  
Eiji Niwa
Keyword(s):  
Amino Acid ◽  
Thermal Behavior ◽  
Muscle Protein ◽  
Basic Amino Acid ◽  
Amino Acid Residues

Peroxisome targeting signal of rat liver acyl-coenzyme A oxidase resides at the carboxy terminus

1989 ◽  
Vol 9 (1) ◽  
pp. 83-91
Author(s):  
S Miyazawa ◽  
T Osumi ◽  
T Hashimoto ◽  
K Ohno ◽  
S Miura ◽  
...  
Keyword(s):  
Amino Acid ◽  
Rat Liver ◽  
Coenzyme A ◽  
Terminal Region ◽  
Proteinase K ◽  
Amino Acid Residues ◽  
C Terminus ◽  
Targeting Signal ◽  
Acyl Coenzyme A

To identify the topogenic signal of peroxisomal acyl-coenzyme A oxidase (AOX) of rat liver, we carried out in vitro import experiments with mutant polypeptides of the enzyme. Full-length AOX and polypeptides that were truncated at the N-terminal region were efficiently imported into peroxisomes, as determined by resistance to externally added proteinase K. Polypeptides carrying internal deletions in the C-terminal region exhibited much lower import activities. Polypeptides that were truncated or mutated at the extreme C terminus were totally import negative. When the five amino acid residues at the extreme C terminus were attached to some of the import-negative polypeptides, the import activities were rescued. Moreover, the C-terminal 199 and 70 amino acid residues of AOX directed fusion proteins with two bacterial enzymes to peroxisomes. These results are interpreted to mean that the peroxisome targeting signal of AOX residues at the C terminus and the five or fewer residues at the extreme terminus have an obligatory function in targeting. The C-terminal internal region also has an important role for efficient import, possibly through a conformational effect.

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