Protein Analysis, Chemistry & Engineering
SunnyLand applies protein chemistry, analysis and engineering to biology and medicine.
One program is “Hybrid Modality Engineering of Proteins”—a platform to introduce non-canonical chemical moieties and/or scaffolds into peptides and proteins to confer novel functions (mode of action) otherwise unavailable via recombinant technology.
The second is to devise chemo-enzymatic methodologies to characterize protein modifications (PTMs), such as crosslinking, isoaspartic acid formation (asparagine deamidation), S-adenosyl-methionine (AdoMet or SAM)-dependent methylations, and moreover, unknown PTMs. In collaboration with biologists and clinicians alike, we also investigate PTM biological effects, and moreover, as critical attributes in protein pharmaceuticals.
A third program area is the mechanistic studies of and inhibitor design for enzymes with intriguing mechanisms and biomedical significance.
Homogeneous photoimmunoconjugates that can enable cancer cell-targeted photodynamic therapy were synthesized. The antibody was first conjugated with an amino linker containing a clickable handle via a site-specific modification of glutamine residues catalyzed by transglutaminase enzyme (TGase, EC 18.104.22.168). In a second step, conjugation to a fluorescent dye was performed by click chemistry. This approach avoids modification on the antigen-binding fragment (Fab) and site-specifically modifies a glutamine on the crystallizable fragment (Fc).
Photodynamic Switches for Proteins
Amine-containing photoremovable chromaphores were incorporated into proteins at available glutamine residues catalyzed by transglutaminase enzyme (TGase, EC22.214.171.124). Subsequently, photolysis regenerated the native proteins. Protein modifications that reduce or abolish activities are referred to as “caging”, and photoremoval of modifications is “uncaging”.
Selenium Analog of S-Adenosyl-L-homocysteine
The synthesis and redox chemistry of Se-adenosyl-L-selenohomocysteine (SeAH) were investigated. This is the selenium analog of the endogenous sulfur compound S-adenosylhomocysteine (SAH or AdoHcy).
Brominated coumarin azide can be used to tag alkynes and detect alkyne-conjugated biomolecules. This tag has several useful properties: first, it is fluorogenic and the click-chemistry products are highly fluorescent and quantifiable; second, its distinct isotopic pattern facilitates identification by mass spectrometry; and third, its click-chemistry products form a unique pair of reporter ions upon fragmentation that can be used for the quick screening of data.
Coupling Assay of SAMT Activity
The TNB generate from the coupled assay is quantified by absorption at 412 nm using a microplate reader
Quorum Sensing Inhibition
Quorum sensing is a process by which bacteria sense cell density. Shown here is the synthesis of two substrate analogues, S-anhydroribosyl-l-homocysteine and S-homoribosyl-l-cysteine, which prevent the initial and final step of the mechanism, respectively.