11 research outputs found
The Gene Ontology knowledgebase in 2023
The Gene Ontology (GO) knowledgebase (http://geneontology.org) is a comprehensive resource concerning the functions of genes and gene products (proteins and noncoding RNAs). GO annotations cover genes from organisms across the tree of life as well as viruses, though most gene function knowledge currently derives from experiments carried out in a relatively small number of model organisms. Here, we provide an updated overview of the GO knowledgebase, as well as the efforts of the broad, international consortium of scientists that develops, maintains, and updates the GO knowledgebase. The GO knowledgebase consists of three components: (1) the GO-a computational knowledge structure describing the functional characteristics of genes; (2) GO annotations-evidence-supported statements asserting that a specific gene product has a particular functional characteristic; and (3) GO Causal Activity Models (GO-CAMs)-mechanistic models of molecular "pathways" (GO biological processes) created by linking multiple GO annotations using defined relations. Each of these components is continually expanded, revised, and updated in response to newly published discoveries and receives extensive QA checks, reviews, and user feedback. For each of these components, we provide a description of the current contents, recent developments to keep the knowledgebase up to date with new discoveries, and guidance on how users can best make use of the data that we provide. We conclude with future directions for the project
Signal Amplification in Enzyme-Based Amperometric Biosensors
A unique mode of current amplification
was investigated in reagentless
biosensors based on the clinically significant enzymes including alcohol
dehydrogenase, glucose 6-phosphate dehydrogenase, glycerol 3-phosphate
dehydrogenase, and glucose oxidase. The biosensors were designed by
sandwiching the enzyme–polymer film between an electrode and
Nafion film. In particular, each enzyme and its cofactor were covalently
attached to the chains of polysaccharide chitosan and mixed with carbon
nanotubes on the electrode surface. The coating of such biosensors
with Nafion resulted in the current increase by up to 1000%, depending
on the enzyme. The results were analyzed considering the interplay
between the enzyme activity–pH profiles and the Nafion-induced
pH increase in the underlying chitosan film. The data were collected
by using the rapid (<5 min) amperometric enzyme assays and pH-sensitive
iridium oxide films. The increase in the biosensor current was attributed
to the pH-driven increase in the enzyme activity inside the two-film
interface. Such signal amplification should also be feasible in other
biosensors based on the polyelectrolytes and sandwiched enzymes providing
that a proper match is made between the enzyme activity–pH
profiles and the pH of buffer solutions
Electrochemical Coupled-Enzyme Assays at Carbon Nanotubes
The recently developed internally
calibrated electrochemical continuous
enzyme assay (ICECEA) has proved to work well for single-enzyme systems.
In the present work, its relevance to more challenging coupled-enzyme
measurements was investigated by using a model enzyme pair comprising
aspartate transaminase (AST) and malic dehydrogenase. The ICECEA was
performed at an electrode modified with carbon nanotubes (CNTs), which
were dispersed in a polysaccharide chitosan that acted as an adhesive.
The 7 min assay required a 100 ÎĽL sample and relied on an AST-free
calibration. It had a limit of detection equal to 5.0 pM AST (0.10
U L<sup>–1</sup>) with no need for the incubation period. Its
linear range extended up to 3500 pM (70 U L<sup>–1</sup>).
Perhaps the most promising was the fact that the assay and its calibration
could be performed in the same solution even though the composition
of the assay solution for the coupled-enzyme assays is typically more
complex than that for the single-enzyme assays. This and the fast
electrode kinetics of the signal transducing reaction of nicotinamide
adenine dinucleotide at CNTs accounted for the low limit of detection.
The unique shape of the ICECEA amperogram allowed for the selective
determination of AST in the complex matrix of serum samples containing
redox active potentially interfering species. Given these advantages,
the prospects for the ICECEA in the development of other coupled-enzyme
assays were also discussed
Rapid Electrochemical Enzyme Assay with Enzyme-Free Calibration
The
internally calibrated electrochemical continuous enzyme assay (ICECEA,
patent pending) was developed for the fast determination of enzyme
activity unit (<i>U</i>). The assay depends on the integration
of enzyme-free preassay calibration with the actual enzyme assay in
one continuous experiment. Such integration resulted in a uniquely
shaped amperometric trace that allowed for the selective picomolar
determination of redox enzymes. The ICECEA worked because the preassay
calibration did not interfere with the enzyme assay allowing both
measurements to be performed in succession in the same solution and
at the same electrode. The method displayed a good accuracy (relative
error, <3%) and precision (relative standard deviation (RSD), <3%)
when tested with different working electrodes (carbon nanotubes/chitosan,
glassy carbon, platinum) and enzymes (alcohol dehydrogenase, ADH;
lactate dehydrogenase, LDH; xanthine oxidase, XOx; glucose oxidase,
GOx). The limit of detection for the ADH, LDH, XOx, and GOx was equal
to 0.18, 0.14, 0.0031, and 0.11 U L<sup>–1</sup> (or 4.2, 0.72,
89, and 6.0 pM), respectively. The simplicity, reliability, and short
analysis time make the ICECEA competitive with the optical enzyme
assays currently in use
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The Gene Ontology knowledgebase in 2023
The Gene Ontology (GO) knowledgebase (http://geneontology.org) is a comprehensive resource concerning the functions of genes and gene products (proteins and noncoding RNAs). GO annotations cover genes from organisms across the tree of life as well as viruses, though most gene function knowledge currently derives from experiments carried out in a relatively small number of model organisms. Here, we provide an updated overview of the GO knowledgebase, as well as the efforts of the broad, international consortium of scientists that develops, maintains, and updates the GO knowledgebase. The GO knowledgebase consists of three components: (1) the GO-a computational knowledge structure describing the functional characteristics of genes; (2) GO annotations-evidence-supported statements asserting that a specific gene product has a particular functional characteristic; and (3) GO Causal Activity Models (GO-CAMs)-mechanistic models of molecular "pathways" (GO biological processes) created by linking multiple GO annotations using defined relations. Each of these components is continually expanded, revised, and updated in response to newly published discoveries and receives extensive QA checks, reviews, and user feedback. For each of these components, we provide a description of the current contents, recent developments to keep the knowledgebase up to date with new discoveries, and guidance on how users can best make use of the data that we provide. We conclude with future directions for the project
The Gene Ontology Knowledgebase in 2023
: The Gene Ontology (GO) knowledgebase (http://geneontology.org) is a comprehensive resource concerning the functions of genes and gene products (proteins and non-coding RNAs). GO annotations cover genes from organisms across the tree of life as well as viruses, though most gene function knowledge currently derives from experiments carried out in a relatively small number of model organisms. Here, we provide an updated overview of the GO knowledgebase, as well as the efforts of the broad, international consortium of scientists that develops, maintains and updates the GO knowledgebase. The GO knowledgebase consists of three components: 1) the Gene Ontology - a computational knowledge structure describing functional characteristics of genes; 2) GO annotations - evidence-supported statements asserting that a specific gene product has a particular functional characteristic; and 3) GO Causal Activity Models (GO-CAMs) - mechanistic models of molecular "pathways" (GO biological processes) created by linking multiple GO annotations using defined relations. Each of these components is continually expanded, revised and updated in response to newly published discoveries, and receives extensive QA checks, reviews and user feedback. For each of these components, we provide a description of the current contents, recent developments to keep the knowledgebase up to date with new discoveries, as well as guidance on how users can best make use of the data we provide. We conclude with future directions for the project