scholarly journals Three Structural Features of Functional Food Components and Herbal Medicine with Amyloid β42 Anti-Aggregation Properties

Molecules ◽  
2019 ◽  
Vol 24 (11) ◽  
pp. 2125 ◽  
Author(s):  
Kazuma Murakami ◽  
Kazuhiro Irie
Keyword(s):  
Amino Acid ◽  
Functional Food ◽  
Structural Characteristics ◽  
Salt Bridge ◽  
Basic Amino Acid ◽  
Structural Features ◽  
Amino Acid Residues ◽  
Treatment And Prevention ◽  
Food Components ◽  
Underlying Mechanisms

Aggregation of amyloid β42 (Aβ42) is one of the hallmarks of Alzheimer’s disease (AD). There are numerous naturally occurring products that suppress the aggregation of Aβ42, but the underlying mechanisms remain to be elucidated. Based on NMR and MS spectroscopic analysis, we propose three structural characteristics found in natural products required for the suppressive activity against Aβ42 aggregation (i.e., oligomerization by targeting specific amino acid residues on this protein). These characteristics include (1) catechol-type flavonoids that can form Michael adducts with the side chains of Lys16 and 28 in monomeric Aβ42 through flavonoid autoxidation; (2) non-catechol-type flavonoids with planarity due to α,β-unsaturated carbonyl groups that can interact with the intermolecular β-sheet region in Aβ42 aggregates, especially aromatic rings such as those of Phe19 and 20; and (3) carboxy acid derivatives with triterpenoid or anthraquinoid that can generate a salt bridge with basic amino acid residues such as Lys16 and 28 in the Aβ42 dimer or trimer. Here, we summarize the recent body of knowledge concerning amyloidogenic inhibitors, particularly in functional food components and Kampo medicine, and discuss their application in the treatment and prevention of AD.

scholarly journals Structural analyses of the deduced amino acid sequences of a novel type heme–copper terminal oxidase, cytochrome aco3, from alkalophilic Bacillus YN-2000

2001 ◽  
Vol 47 (12) ◽  
pp. 1075-1081 ◽  
Author(s):  
Kimitoshi Denda ◽  
Akira Oshima ◽  
Yoshihiro Fukumori
Keyword(s):  
Amino Acid ◽  
Cytochrome C ◽  
Basic Amino Acid ◽  
Structural Features ◽  
Thermophilic Bacterium ◽  
Amino Acid Sequences ◽  
Amino Acid Residues ◽  
Gene Encoding ◽  
Bacterium Bacillus ◽  
Alkalophilic Bacillus

Cytochrome aco3 from a facultatively alkalophilic bacterium, Bacillus YN-2000, was found to be alkaline- and heat-tolerant. To better understand the structural features of Bacillus YN-2000 cytochrome aco3, the gene encoding this enzyme was cloned and sequenced. Nucleotide sequence analyses of the region neighboring the acoI (subunit I) gene revealed that the acoII (subunit II) and acoIII (subunit III) genes were concomitantly clustered upstream and downstream of the acoI gene, respectively, forming an operon with transcriptional polarity. The deduced amino acid sequence of subunit I was highly similar to that of cytochrome caa3 from thermophilic bacterium Bacillus PS3 in which the heme a3 could be replaced with heme o. Furthermore, a marked paucity of basic amino acid residues was found in the cytochrome c-binding subunit II, which might be a result of the adaptation to a highly alkaline external milieu.Key words: cytochrome c oxidase, alkalophile, thermostability, heme o, Bacilli.

Identification of key residues in the formate channel FocA that control import and export of formate

2014 ◽  
Vol 395 (7-8) ◽  
pp. 813-825 ◽  
Author(s):  
Doreen Hunger ◽  
Claudia Doberenz ◽  
R. Gary Sawers
Keyword(s):  
Amino Acid ◽  
Quaternary Structure ◽  
Salt Bridge ◽  
Structural Features ◽  
Amino Acid Residues ◽  
Form Part ◽  
Import And Export ◽  
Key Residues ◽  
Acid Exchange

Abstract The formate-nitrite transporter (FNT) family comprises pentameric channels that transport monovalent anions. The prototype of this family is the formate channel (FocA), which was originally identified as a formate channel in Escherichia coli. Each protomer in the channel has a pore with structural features that include periplasmic and cytoplasmic constriction sites, which are likely important for bi-directional gating of substrate passage. Highly conserved amino acid residues within FocA previously identified in structural studies are predicted to be important in the control of formate translocation. Here we present a first detailed in vivo analysis of these residues using a combined targeted amino acid exchange and formate-responsive lacZ fusion-based reporter approach. Sixteen exchanges were made and each variant was shown to be largely unaffected in its secondary and quaternary structure. The invariant H209 and T91 residues, which form part of the lower constriction site linking the Ω-loop with the pore cavity, proved to be important in governing the directionality of formate passage through the pore. A predicted salt-bridge triad of E208-K156-N213 along with the cytoplasmically-oriented N-terminal helix are also involved in pH-dependent gating of the channel. Together, our data are consistent with passive export and import of formate or formic acid through the channel.

scholarly journals Primary structures of seven metallothioneins from rabbit tissue

1995 ◽  
Vol 306 (1) ◽  
pp. 265-270 ◽  
Author(s):  
P E Hunziker ◽  
P Kaur ◽  
M Wan ◽  
A Känzig
Keyword(s):  
Amino Acid ◽  
Structural Characteristics ◽  
Structural Features ◽  
Amino Acid Sequences ◽  
Rabbit Kidney ◽  
Amino Acid Residues ◽  
Liver And Kidney ◽  
A Chain ◽  
The Stability ◽  
The Individual

Metallothionein from tissues of rabbits exposed to cadmium chloride was separated into seven distinct isoforms by reverse-phase liquid chromatography and their complete amino acid sequences were determined. Five of the seven isometallothioneins showed structural features so far not identified in other mammalian metallothioneins. Thus, two isoproteins contain a polypeptide with a chain length of 62 rather than 61 amino acid residues. Two isoforms are characterized by an additional positive charge and one by the presence of an isopeptide bond between aspartic acid and serine in the N-terminal half of the protein. The isoproteins characterized were identified from different sources: rabbit liver and kidney and a rabbit kidney cell-line (RK-13). In all three, the structural characteristics of the individual isoforms are retained, indicating that in the different tissues the same mechanisms control the synthesis and the stability of the different cadmium-induced isoMTs.

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 Multiple Distinct Sets of Stereotyped Antigen Receptors Indicate a Role for Antigen in Promoting Chronic Lymphocytic Leukemia

2004 ◽  
Vol 200 (4) ◽  
pp. 519-525 ◽  
Author(s):  
Bradley T. Messmer ◽  
Emilia Albesiano ◽  
Dimitar G. Efremov ◽  
Fabio Ghiotto ◽  
Steven L. Allen ◽  
...  
Keyword(s):  
Amino Acid ◽  
B Cell ◽  
Structural Features ◽  
Lymphocytic Leukemia ◽  
Cell Subpopulation ◽  
Amino Acid Residues ◽  
Antigen Receptors ◽  
Region Gene ◽  
V Region ◽  
Unique Amino Acid

Previous studies suggest that the diversity of the expressed variable (V) region repertoire of the immunoglobulin (Ig)H chain of B-CLL cells is restricted. Although limited examples of marked constraint in the primary structure of the H and L chain V regions exist, the possibility that this level of restriction is a general principle in this disease has not been accepted. This report describes five sets of patients, mostly with unmutated or minimally mutated IgV genes, with strikingly similar B cell antigen receptors (BCRs) arising from the use of common H and L chain V region gene segments that share CDR3 structural features such as length, amino acid composition, and unique amino acid residues at recombination junctions. Thus, a much more striking degree of structural restriction of the entire BCR and a much higher frequency of receptor sharing exists among patients than appreciated previously. The data imply that either a significant fraction of B-CLL cells was selected by a limited set of antigenic epitopes at some point in their development and/or that they derive from a distinct B cell subpopulation with limited Ig V region diversity. These shared, stereotyped Ig molecules may be valuable probes for antigen identification and important targets for cross-reactive idiotypic therapy.

scholarly journals The influence of sex steroid hormones on ferrochelatase gene expression in Harderian gland of hamster (Mesocricetus auratus)

2006 ◽  
Vol 189 (1) ◽  
pp. 103-112 ◽  
Author(s):  
F Vilchis ◽  
L Ramos ◽  
C Timossi ◽  
B Chávez
Keyword(s):  
Amino Acid ◽  
Steroid Hormones ◽  
Protoporphyrin Ix ◽  
Harderian Gland ◽  
Active Role ◽  
Structural Features ◽  
Sex Steroid Hormones ◽  
Sex Steroid ◽  
Amino Acid Residues ◽  
Haem Proteins

Ferrochelatase (protohaem ferrolyase, EC 4.99.1.1), the terminal enzyme of the haem biosynthetic pathway, catalyses the insertion of ferrous iron into protoporphyrin IX to form protohaem. The Syrian hamster Harderian gland (HG) is known for its ability to produce and accumulate large amounts of protoporphyrins. In this species, the female gland contains up to 120 times more porphyrin than the male gland. Data from biochemical studies suggest that this gland possesses the enzymatic complex for haem biosynthesis but lacks ferrochelatase activity. The abundance of intraglandular haem proteins does not support this idea. To gain more insight into this process, we isolated cDNA for ferrochelatase from hamster liver, using the 5′- and 3′- rapid amplification of complementary DNA ends (RACE), and investigated its expression in HG from males and females. The full-length cDNA comprises an open reading frame of 1269 bp encoding a polypeptide of 422 amino-acid residues. Hamster DNA sequence exhibits 92% identity to mouse and 87% identity to human sequences. The predicted hamster enzyme was shown to have structural features of mammalian ferrochelatase, including a putative NH2- terminal presequence, a central core of about 330 amino-acid residues and an extra 30–50-amino-acid stretch at the carboxyl-terminus. RNA blotting experiments indicated that this cDNA hybridized to a liver mRNA of about 2.1 kb, while a weak hybridization signal was observed with mRNA from HG preparations. RT–PCR assays confirmed the expression of specific transcripts in both tissues. Male glands contained approximately twofold more enzyme mRNA than female glands. Likewise, the intraglandular content of mRNA varied during the oestrous cycle, with the highest levels found in the oestrous phase. These cyclic variations were less evident in liver. Ovariectomy plus treatment with progesterone or 17β-oestradiol plus progesterone increased ferrochelatase mRNA of the gland. In HG of short- or long-term castrated males, the administration of testosterone did not affect the ferrochelatase mRNA concentration. Based on mRNA expression levels, we conclude that Harderian ferrochelatase may play an active role in maintaining the physiological pool of haem required for processing cytochromes and other glandular haem proteins. Likewise, the sex-steroid hormones appear to have only a modest influence upon Harderian ferrochelatase.

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
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