In certain embodiments compositions are provided that comprise a pentapeptide comprising the formula: C.sup.1-X.sup.2-X.sup.3-X.sup.4-C.sup.5 where C.sup.1 and C.sup.5 are independently selected cysteines or cysteine analogues, or other amino acids with sidechains suitable for cyclization, where the cysteines or cysteine analogs are attached to each other by a linkage that does not comprise X.sup.2, X.sup.3, and X.sup.4; where X.sup.2, X.sup.3, and X.sup.4 are independently selected amino acids; and the peptide, when administered to a cell alters APP signaling and/or switches APP processing from aberrant to normal. The compositions mitigate amyloid plaque formation.

The present disclosure relates to compositions of immobilized enzymes on the surface of achromosomal and/or anucleate cells and uses thereof. In particular, the present disclosure provides genetically engineered minicells with enzymes self-assembled on their surface. The immobilized enzymes on the surface of achromosomal and/or anucleate minicells, has agricultural, industrial, and environmental applications due to their improved stability durability and, reusability. Also, provided are methods for producing and purifying enzyme-immobilized minicells.