GFP-like non-fluorescent chromoprotein FP595 Antibody

What is the molecular structure of the asFP595 chromoprotein recognized by the antibody?

asFP595 belongs to the family of green fluorescent protein (GFP)-like proteins from Anthozoa species, specifically from Anemonia sulcata (Mediterranean snakelocks sea anemone). Unlike traditional assumptions that these proteins contain an imidazolidinone core similar to GFP, asFP595 forms its chromophore through a distinct process. The protein undergoes a GFP-type cyclization resulting in a p-hydroxybenzylideneimidazolinone moiety formed by specific amino acid residues (Met-65/Gln-66, Tyr-66/67, and Gly-67/68) . Additionally, asFP595 exhibits a unique structural feature: during maturation, the Cys-Met peptide bond adjacent to the chromophore hydrolyzes, splitting the chromoprotein into two fragments of approximately 8 kDa and 20 kDa . This fragmentation is critical for protein maturation and influences antibody recognition sites.

How does the photoswitching mechanism of asFP595 affect antibody binding and experimental design?

asFP595 possesses a remarkable photoswitching capability between a non-fluorescent "off" state and a fluorescent "on" state. X-ray analysis has demonstrated that upon absorption of green light, the chromophore isomerizes from a trans (off) to a cis (on) configuration . This conformational change involves a "bottom hula twist" mechanism with rotation of both bonds of the chromophoric methine ring bridge . For researchers using antibodies against asFP595, this photoswitching property presents unique considerations: antibody binding affinity may differ between the two conformational states, potentially leading to illumination-dependent variation in experimental results. Methodologically, researchers should control illumination conditions during experiments to maintain consistent antibody-epitope interactions and consider validating antibody recognition of both protein states if studying the photoswitching mechanism.

What are the spectral properties of asFP595 that could influence detection methods when using this antibody?

asFP595 exhibits distinct pH-dependent spectral forms that researchers should consider when designing detection protocols. Spectrophotometric titration reveals three pH-dependent forms: yellow (absorption maximum = 430 nm) at pH 3.0; red (absorption maximum = 535 nm) at pH 8.0; and colorless (absorption maximum = 380 nm) at pH 14.0 . The pKa values for these spectral transitions (6.8 and 10.9) correspond to ionization of the phenolic group of dehydrotyrosine and deprotonation of the amidinium cation in the chromophore heterocycle, respectively . When designing experiments using anti-asFP595 antibodies alongside spectroscopic detection, researchers should carefully control buffer pH to maintain consistent chromophore configuration, as conformational changes may affect antibody binding efficiency and epitope accessibility.

What are the recommended applications for the GFP-like non-fluorescent chromoprotein FP595 antibody?

Based on available product information, the GFP-like non-fluorescent chromoprotein FP595 antibody has been validated for specific applications including ELISA (Enzyme-Linked Immunosorbent Assay) and Western Blot (WB) analysis . For optimal results in Western blotting, researchers should consider the fragmented nature of mature asFP595 - the protein cleaves into 8 kDa and 20 kDa fragments during maturation . This fragmentation will result in two distinct bands rather than a single band at the theoretical molecular weight of the full protein. For immunohistochemistry or immunofluorescence applications, though not explicitly validated in the search results, researchers would need to perform optimization experiments with appropriate positive and negative controls to establish protocol specificity.

How should researchers prepare samples to optimize detection of asFP595 using this antibody?

For optimal sample preparation when working with asFP595 and its antibody, researchers should consider the protein's unique structural characteristics. Since asFP595 undergoes spontaneous cleavage between Cys-64 and Met-65 during maturation , sample preparation protocols should preserve both fragments to maintain complete epitope representation. For Western blotting, use non-reducing or mildly reducing conditions initially, as strong reducing agents might disrupt important structural epitopes. Buffer systems should be maintained at pH 7.5-8.0 to stabilize the red spectral form of the protein (absorption maximum = 535 nm) . When extracting asFP595 from recombinant sources, mild lysis conditions using buffer systems containing 50 mM Tris-HCl, 150 mM NaCl, and protease inhibitors are recommended to preserve protein integrity while minimizing degradation of the chromophore structure.

What controls should be included when using this antibody for Western blotting or immunodetection?

For rigorous scientific experiments using the GFP-like non-fluorescent chromoprotein FP595 antibody, multiple controls should be implemented. Positive controls should include purified recombinant asFP595 protein , which would demonstrate the antibody's specific binding capacity and reveal the characteristic pattern of fragmentation (8 kDa and 20 kDa bands). For negative controls, researchers should include samples from non-transfected cells or tissues without asFP595 expression. Additionally, a peptide competition assay using the immunogen peptide (recombinant Anemonia sulcata GFP-like non-fluorescent chromoprotein FP595) would confirm binding specificity by demonstrating signal reduction when the antibody is pre-incubated with excess antigen. For cross-reactivity assessment, include samples containing other GFP-family proteins to verify the antibody doesn't recognize related fluorescent proteins from the same family.

What are the implications of the protein backbone break in asFP595 for antibody-based detection methods?

The unexpected protein backbone break between Cys-64 and Met-65 in mature asFP595 represents a unique challenge for antibody-based detection. This breakpoint creates two distinct polypeptide chains (referred to as chain 1 and chain 2) , which remain associated in the native protein structure but may separate under denaturing conditions. For researchers developing detection protocols, this fragmentation has several methodological implications:

• Western Blotting: Expected migration patterns will show two distinct fragments rather than a single band, with apparent molecular weights of approximately 8 kDa and 20 kDa .

• Epitope Recognition: Antibodies generated against peptide sequences spanning the Cys-64/Met-65 junction will likely show reduced affinity for the mature protein.

• Native vs. Denatured Detection: The difference in antibody recognition between native and denatured samples may be pronounced if the epitope includes regions from both fragments that remain in proximity only in the native structure.

To address these challenges, researchers should verify which fragment(s) their antibody recognizes and consider using multiple antibodies targeting different regions when working with this protein.

How can the photoswitching properties of asFP595 be leveraged for advanced imaging techniques using antibody-conjugated systems?

The reversible photoswitching capability of asFP595 between fluorescent and non-fluorescent states offers unique opportunities for advanced imaging applications when combined with antibody-based detection. Molecular dynamics simulations and crystal structure analysis have revealed that asFP595 switches from trans (off) to cis (on) conformation upon absorption of green light, while blue light reverses this process . This photochromic property can be methodologically exploited in several ways:

• Super-resolution Microscopy: By conjugating anti-asFP595 antibodies with secondary fluorophores, researchers can develop photoactivation localization microscopy (PALM) protocols where controlled illumination activates only subsets of molecules at a time.

• Protein Tracking Studies: The controlled photoswitching allows for precise temporal control of fluorescence, enabling pulse-chase experiments to track protein movement within cellular compartments.

• Multiplexed Imaging: The distinct spectral properties of asFP595 (absorption maxima at 430 nm, 535 nm, or 380 nm depending on pH) provide opportunities for multiplexed imaging when combined with other fluorophores.

Implementation requires careful optimization of illumination parameters (wavelength, intensity, duration) and consideration of the spontaneous relaxation of the on state back to the off state in standard asFP595 variants.

What factors might affect the sensitivity and specificity of the FP595 antibody in experimental systems?

Several key factors can influence the performance of anti-FP595 antibodies in research applications. The unique structural characteristics and photoswitching properties of asFP595 present specific technical challenges:

To optimize experimental outcomes, researchers should characterize their specific antibody against these parameters and establish consistent protocols for sample handling and analysis conditions .

How do post-translational modifications and maturation state of asFP595 affect antibody recognition?

Methodologically, researchers should consider these maturation states when designing experiments:

• Immature asFP595 (full-length polypeptide with forming chromophore)

• Mature fragmented asFP595 with intact imino moiety

• Fully mature asFP595 with hydrolyzed oxo group

Antibody recognition may vary considerably between these states. To account for this variability, researchers should determine which maturation state their antibody preferentially recognizes using western blotting or immunoprecipitation of time-course samples during protein expression. For applications requiring detection of all maturation states, a mixture of antibodies targeting different epitopes may be necessary.

What are the recommended storage and handling procedures to maintain antibody efficacy when working with this photosensitive protein system?

To maintain optimal antibody efficacy when working with the photosensitive asFP595 system, researchers should implement specific storage and handling procedures that account for both antibody stability and the unique properties of the target protein:

• Antibody Storage: Store antibodies at -20°C in small aliquots to minimize freeze-thaw cycles . For diluted working solutions, add preservatives such as 0.03% Proclin 300 to prevent microbial contamination .

• Light Protection: Since asFP595 is photoswitchable between states, store both antibody and protein samples in amber tubes or wrapped in aluminum foil to prevent unintended photoswitching during storage and handling.

• Temperature Considerations: While standard antibody storage temperatures apply (-20°C for long-term storage), samples containing intact asFP595 protein should be maintained at consistent temperatures, as temperature fluctuations may affect chromophore configuration and thus epitope structure.

• Buffer Composition: For applications involving detection of native asFP595, use Tris/PBS-based buffers (pH 8.0) with 5-50% glycerol for stabilization . This pH optimizes the red spectral form of the protein.

• Reconstitution of Lyophilized Antibodies: When reconstituting lyophilized antibody preparations, use sterile buffers and allow complete dissolution at 4°C before use to ensure proper antibody structure restoration.

By following these methodological guidelines, researchers can maintain consistent antibody performance while accounting for the unique photosensitive properties of the asFP595 system.

How does the asFP595 antibody performance compare with antibodies against other GFP-like proteins in research applications?

When comparing the GFP-like non-fluorescent chromoprotein FP595 antibody with antibodies against other GFP-family proteins, several unique considerations emerge due to asFP595's distinctive structural and spectral properties. Unlike traditional GFP antibodies that recognize a stable β-barrel structure with an intact chromophore, anti-asFP595 antibodies must contend with a target that undergoes backbone fragmentation during maturation . This characteristic affects experimental outcomes in several ways:

• Epitope Stability: While GFP antibodies typically recognize stable epitopes, asFP595 antibodies must accommodate structural changes resulting from the Cys-64/Met-65 cleavage. This may result in maturation-dependent variations in detection sensitivity that are not observed with standard GFP antibodies.

• Photoswitching Considerations: Unlike constitutively fluorescent GFP variants, asFP595's photoswitchable nature means its conformation changes significantly between off and on states . This conformational change may affect antibody binding in ways not experienced with standard GFP antibodies.

• Spectral State Dependence: The pH-dependent spectral states of asFP595 (yellow, red, or colorless) present additional variables not typically considered when working with GFP antibodies.

For optimal experimental design, researchers should specifically validate anti-asFP595 antibodies for their particular application rather than applying protocols developed for standard GFP antibodies.

What are the emerging applications of asFP595 antibody in super-resolution microscopy and protein dynamics studies?

The unique photoswitching properties of asFP595 offer exceptional opportunities for cutting-edge microscopy applications when combined with specific antibodies. The reversible photoconversion between non-fluorescent and fluorescent states makes this system particularly valuable for super-resolution techniques and protein dynamics studies.

For super-resolution microscopy applications, anti-asFP595 antibodies can be employed in several innovative approaches:

• PALM/STORM Imaging: By exploiting the controlled photoactivation of asFP595 with green light (and reversion with blue light) , researchers can achieve precise temporal control over fluorescence emission. This enables single-molecule localization microscopy with enhanced spatial resolution beyond the diffraction limit.

• Pulse-Chase Protein Tracking: The ability to specifically activate subpopulations of asFP595-tagged proteins allows for precise tracking of protein cohorts throughout cellular compartments, providing insights into protein trafficking and turnover rates.

• Correlative Light-Electron Microscopy: Anti-asFP595 antibodies conjugated with both fluorophores and electron-dense particles enable correlative imaging across platforms, bridging high-resolution structural information with functional fluorescence data.

Methodologically, these applications require precise control over illumination conditions and careful antibody conjugation strategies to maintain both photoswitching functionality and specificity. Researchers implementing these techniques should develop specialized imaging protocols that account for the spontaneous relaxation of asFP595 from the on to the off state.

How can researchers optimize multiplex detection systems incorporating both asFP595 antibodies and other fluorescent protein antibodies?

Developing effective multiplex detection systems that incorporate anti-asFP595 antibodies alongside antibodies against other fluorescent proteins requires careful consideration of several technical factors. The unique properties of asFP595, particularly its photoswitching behavior and spectral characteristics, necessitate specific optimization strategies:

• Spectral Separation Strategy: asFP595 in its on state has an emission maximum distinct from common fluorescent proteins like GFP and RFP. When designing multiplex experiments, researchers should:

  • Select secondary antibody fluorophores with minimal spectral overlap with the asFP595 emission spectrum

  • Consider the pH-dependent spectral shifts of asFP595 (yellow at pH 3.0, red at pH 8.0) when planning detection channels

  • Implement appropriate spectral unmixing algorithms for channels with partial overlap

• Illumination Protocol Development: Since asFP595 photoswitches between states upon exposure to specific wavelengths (green light for activation, blue light for deactivation) , researchers must carefully coordinate imaging sequences to prevent unintended state changes during detection of other fluorophores.

• Antibody Compatibility Assessment: When combining multiple antibodies for multiplex detection:

  • Verify that antibody pairs can be used concurrently without cross-reactivity

  • Establish a sequential staining protocol if antibodies are incompatible

  • Validate that detection reagents for one target do not interfere with photoswitching properties of asFP595

By systematically addressing these factors, researchers can develop robust multiplex detection systems that leverage the unique properties of asFP595 alongside other fluorescent protein markers.