Subunit Stoichiometry Analysis
Subunit Stoichiometry Analysis - Related Videos
02:57
Reaction Stoichiometry
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2020
A balanced chemical equation provides a great deal of information in a very succinct format. Chemical formulas provide the identities of the reactants and products involved in the chemical change, allowing classification of the reaction. Coefficients provide the relative numbers of these chemical species, allowing a quantitative assessment of the relationships between the amounts of substances consumed and produced by the reaction. These quantitative relationships are known as the reaction’s...
03:40
Stoichiometry, Product Yield, and Limiting Reactants - Concepts
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2020
Chemical equations represent how a chemical reaction proceeds from reactants to products through physical or chemical change using chemical formulas. Stoichiometry is a term that describes the relative quantities of reactants and products in a chemical reaction. It is based on the Law of Conservation of Mass, which is a fundamental law that states that matter is neither created nor destroyed. Quite simply, the number and identity of reactant atoms must equal the number and identity of product...
16:03
Stoichiometry, Product Yield, and Limiting Reactants - Student Protocol
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2020
Source: Smaa Koraym at Johns Hopkins University, MD, USA Synthesis of tris(ethylenediamine)nickel chlorideExpand In this lab, you will combine nickel chloride hexahydrate and ethylenediamine in water to produce tris(ethylenediamine)nickel chloride. When nickel chloride hexahydrate dissolves in water, it rearranges to become the hexaaquanickel cation and two chloride anions. Adding ethylenediamine results in three ethylenediamine molecules exchanging with the six water molecules. This...
03:12
Chemical Stoichiometry and Gases: Using Ideal Gas Law to Determine Moles
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2020
Chemical stoichiometry describes the quantitative relationships between reactants and products in chemical reactions. In addition to measuring quantities of reactants and products using masses for solids and volumes in conjunction with the molarity for solutions; now, the gas volumes can also be used to indicate quantities. If the volume, pressure, and temperature of a gas is known, then the ideal gas equation to calculate how many moles of the gas are present, can be used. Conversely, if the...
06:09
In Vitro Reassociation Assay to Measure the Formation of 80S Ribosomal Particles Using Salt-washed Ribosomal Subunits
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2025
Here, we describe a detailed protocol for the in vitro reassociation of purified, salt-washed eukaryotic ribosomal subunits for the analysis of 80S particle formation. This method is illustrated by analyzing ribosomal subunits isolated from a wild-type strain of Saccharomyces cerevisiae and a mutant strain deficient in the ribosomal protein eL24.
FAQs
The analysis compares the measured composition of an intact assembly with the subunits expected to contribute to it. Agreement across measurements can support a defined, stable complex, whereas variable composition or inconsistent abundance may indicate weaker or transient association. This distinction helps researchers evaluate whether a proposed molecular assembly represents a persistent functional unit or a condition-dependent interaction.
Intact-complex measurements provide a test of assembly models rather than relying only on the identities of individual proteins. If the measured mass or abundance matches a particular combination of subunits, that model gains support; discrepancies can suggest missing components, alternative stoichiometries, or changes in assembly. This comparison therefore connects molecular composition with structural and functional organization.
Changes in ligand binding, protein sequence, or cellular conditions may alter which subunits associate or the relative amount of each subunit in a complex. Subunit Stoichiometry Analysis can reveal these composition changes by comparing measurements under different conditions. Such comparisons help determine whether a regulatory factor affects complex assembly itself or changes the behavior of an already formed assembly.
Native mass spectrometry measures intact assemblies under conditions intended to preserve their associated subunits, while analytical ultracentrifugation examines their behavior in solution. Each approach provides a different measurement basis for evaluating complex composition. Using either method, or comparing results across methods, can strengthen conclusions about the number and relative proportions of subunits in a molecular assembly.
Size-exclusion chromatography separates molecular assemblies according to their solution behavior and can help distinguish an intact complex from free or differently assembled components. Researchers can examine the resulting fractions with quantitative biochemical assays to compare subunit abundance across separated species. This workflow is useful when composition must be assessed alongside the presence of distinct assembly states.
Quantitative biochemical assays are useful when researchers need to compare the relative abundance of identified subunits, either within a purified assembly or across experimental conditions. They can complement measurements of intact-complex mass or solution behavior by testing whether component proportions fit a proposed assembly model. This makes them relevant for evaluating regulatory, mutant, or condition-dependent changes in composition.
These measurements support investigations of enzyme regulation, membrane proteins, signaling assemblies, and broader macromolecular architecture. In each setting, the central question may concern whether a complex has a defined composition, whether its assembly changes with a perturbation, or how subunit organization relates to function. The resulting stoichiometric information helps connect molecular architecture with biochemical behavior.