The Fall of Constantinople was one of the most significant events in world history. If you pick up a mainstream historical text-(be it a high school text, college text or even a graduate school text), many Western historians will often say that The Fall of Constantinople was the official starting point of The Modern Western Age, beginning in the year...1453.
(I tend to disagree with such a mainstream scholarly position in that I believe that it was The Northern Italian Renaissance, beginning in the year 1400, which catalyzed The Modern Western Age and its intellectual/cultural identity. True, The Fall of Constantinople greatly allowed for the acceleration and refinement of The Northern Italian Renaissance; though Byzantium's collapse, from my perspective, is secondary, as to when one should accurately chronicle the origin of The Modern West).
In addition to the historical nexus between Constantinople's collapse and Northern Italy's ascendancy-(especially with its intellectual/cultural ascendance in Florence and Venice), The Fall of Constantinople-(a.k.a. the collapse of The Byzantine Empire), also had a profound impact on a number of budding superpowers and empires. The first empire to benefit from Byzantium's collapse, was obviously the Ottoman Empire, the second power to benefit from Byzantium's collapse was the above mentioned Northern Italy, though other superpowers, such as Tsarist Russia, would come to identify itself as "The Third Rome"-(referring to the legacy of Constantinople) and yes, even the Iberian powers from the more distant Western Mediterranean region, would also greatly benefit from Byzantium's collapse.
By the year 1500, it had been nearly 50 years since The Fall of Constantinople and the birth of the Ottoman Empire. During this time, the age of exploration kicked off and led to the vast oceanic and continental expansion of Spain and Portugal.
For the Spanish and the Portuguese, much of the Mediterranean region was "off limits". Both the Ottoman and even the smaller, but still powerful, Venetian and Genoese mercantile empires, controlled the entirety of the Eastern Mediterranean region, as well as the greater Middle Eastern region, thereby blocking larger waterway routes, such as the Dardanelles/Hellespont, the Bosporus and the Nile River.
But, the Western Mediterranean region was essentially, an unoccupied and unconquered waterway zone which allowed for free, uninterrupted exploratory and navigational opportunities. Such an opportunity allowed The Iberian Powers to literally sail westward through The Straits of Gibraltar, as well as the Atlantic Ocean. Perhaps if the Genoese and Venetian Italian mercantilist empires and/or the Ottoman Empire had conquered the Western Mediterranean region, the Iberian powers may not have had such an opportunity for vast oceanic and continental exploration-(and conquest).
In the case of Christopher Columbus-(the man who NEVER discovered America, though had discovered the AmericaS), one must remember that he was NOT of Iberian ethnic descent-(that is to say, he was neither of Spanish, nor Portuguese ethnic descent, but, was of Genoese Italian descent). While it has never really been proven, it has been speculated by a few historians that Christopher Columbus and/or members of his family, had routinely sailed back and forth between his native Genoa and the Aegean islands-(especially, to the island of Chios....of Homeric fame). Many of these Aegean islands, were, at the time, under Genoese Italian mercantilist control until the early-mid 1500's when they fell to the Ottomans. If there is any historical legitimacy or truth to this claim, then it may broaden our understanding of Christopher Columbus' biography and seeing him more as a man with deep Mediterranean ethnic and cultural roots, who was personally aware of the burgeoning influence and power of The Ottomans and as a result, (both he, as well as the Iberian monarchs), looked elsewhere for an alternate route to the East Indies. Such an unconventional view may debunk the more mainstream (and embellished) view of Christopher Columbus as a man who happened to have been from Genoa, Italy, who lived in Spain for a short time and then "sailed the ocean blue" reaching what he believed to have been India-(or Sri Lanka), though instead, had inadvertently and unwittingly "discovered" America.
Overall, when looking at The Fall of Constantinople and birth of The Ottoman Empire, one should try to view such an event more contextually and broadly, especially with regard to its consequential role and influence on the geopolitics of the greater Mediterranean region and the larger world events that would ensue.